The list on the following pages includes about seven hundred genera of plants. Since a single genus may comprise one, fifty, or hundreds of species and varieties, the list could serve as your guide for propagating thousands of plants. The information is general but usually applies to all of the members of the genus. Special cultural notes accompany genera, such as Hibiscus, in which there are hardy, tender, woody, and herbaceous annual and perennial species.
The propagation methods are listed in the same order that they appear in the book: sexual propagation is followed by vegetative practices. The cultural information begins by indicating if the plant may be started from seeds and the necessary procedures, such as conditioning, temperature, and timing (see Sowing Summary). The vegetative practices begin with stem cuttings and end with root cuttings.
Many plants that are potentially invasive, and often easy to propagate, are not included in this list. Examples include certain members of the mint family, running bamboo and other grasses, plume poppy, Perilla, Polygonum, Ranunculus (buttercup), and purple loosestrife.
The commercially prepared seed packets for the most common annual flowers and vegetables nearly always include detailed propagation instructions. These easy plants are not included in the list.
Conversions: 50° F=10° C, 60° F=15.5° C, 70° F=21° C, 80° F=26.5° C.
Note: Gibberillic acid (GA3) is a form of the plant hormone gibberillin, which has been used to overcome physiological germination inhibitors in some species. For example, certain seeds that normally require months of chilling, germinate immediately after soaking in the weakest effective solutions of 100 to 1,000 ppm of GA3 (12 to 48 hours—until they swell). For more information, consult the works of Norman C. Deno (see Bibliography).
ENTRY PARTICULARS
SEED most often refers to species, since most cultivars will not be true to type from sown seed. Heirloom strains will come true, however, if grown away from other members in the species. In all cases, seeds should be completely clean of fruit (moist or dry).
LIGHT calls for surface sowing and exposure to light.
DARK calls for opaque covers for pots or soil over seeds in situ. Check pots for germination—when covers must be removed.
IN SITU refers to sowing seeds where they are intended to grow outdoors. Plants started this way are often ones that are easy to sow, but in some cases, the plants may resent transplanting, such as ones with long taproots. (Many hardy annuals are sown in situ in winter, while some perennials and biennials can be sown in situ from spring through summer to overwinter in place and bloom the following year.)
OUTDOORS does not refer to the open but to the recommended procedure of placing sown seeds in pots in a prepared screen-covered frame in a sheltered or protected location. Most seeds of hardy plants are sown when ripe or in autumn outdoors. They require little care, but moisture in the medium should be checked. (To accelerate the process, pots of some hardy plants may be brought indoors in spring to a location with high humidity, full sun, and cool temperatures [50° F], or they may be placed in a cold frame.)
SOAK is in room-temperature water (unless otherwise specified) and is followed by number of hours and/or temperature of the water, which means the temperature of the water at the outset. If the water should remain at a specific temperature, that will be noted or, in some cases, simply indicated as “warm soak”—above 70° F. For seeds that soak longer than one day, the water should be changed at least once a day. Nearly all seeds of perennial plants received dry in the mail will benefit from a one-hour soak prior to sowing. Once moistened, all seeds must continue the processes leading to germination: they dry, they die.
MOIST-WARM refers to 70–75° F stratification. Seeds can be placed on moist paper towel or moss, or sown in pots prior to treatment.
MOIST-COLD refers to stratification at 40° F (in the refrigerator).
SCARIFICATION means nicking or filing the seed coat, unless otherwise noted. When the coat of a seed seems rock-hard, you can surmise that it may need scarification.
INDOORS, followed by “(temperature),” refers to heated locations—usually under fluorescent lights inside the home or in a greenhouse—and the temperature range for optimal germination. Means must be provided to raise and maintain high relative humidity levels. Plants appreciate lower temperatures at night and after sprouting.
SPORES need to be surface-sown following instructions here.
GERM. DAYS indicates when the first seedlings can be expected to emerge. A wide range of days often means that germination is erratic. The lowest number of days tells you when to begin checking, and the longest number of days might suggest when to abandon hope and discard the seeds and medium.
HERBACEOUS STEM CUTTINGS are ones taken of soft growth usually in the spring, or from new growth that emerges later on non-flowering parts of herbaceous plants that is soft and roots readily. If special recommendations call for taking stem-tip, nodal, or internodal cuttings (below), that will be noted.
SEMI-RIPE refers to the hardened growth from herbaceous plants in summer to late summer.
SOFTWOOD CUTTINGS are sections of stem taken from woody plants when the new growth has ceased elongating and is turgid but is still pliable and tender.
GREENWOOD refers to the new growth on woody plants as it hardens and the stems begin to take on the color of mature growth.
SEMI-RIPEWOOD is the late-season growth of woody plants and is most often used for cuttings of broad-leaved evergreens.
NODAL CUTTINGS are ones trimmed just below a leaf node, and they may be suggested for plants that are prone to rot, or that have hollow or pithy stems, as these will be closed at the node area.
INTERNODAL CUTTINGS are made with cuts between two nodes.
HEEL, MALLET refer to specific cuts on the distal end of a cutting, some of which include a bit of the older stem along with the new harvested tissue (see here).
SECTIONS OF BULBS, CORMS, TUBERS, OR RHIZOMES are cut pieces of geophytes. Bulb sections include a scale and bit of basal plate. The others must have an eye (dormant bud).
DIVISION often refers to cutting through the crown of herbaceous perennials just before or shortly after spring-growth begins. (Where winters are mild and summers hot, perennials can also be divided in autumn, as can very hardy ones in cold climates when mulch is required.) Reference to division via suckers, offets, and runners follows.
BASAL CUTTINGS are ones taken at crown level around the basal rosette of an herbaceous plant—usually late winter or late summer.
ROOT CUTTINGS are taken as described on pages 216–220. (For plants that resent disturbance, such as Eryngium [sea holly], roots suitable for harvesting can be encouraged by potting the plants in containers with large drainage holes and setting the pots about 1 inch into a 3- to 6-inch-deep bed of moist sand. Large roots will grow into the medium, which can be harvested.)
GENERIC GUIDE TO PROPAGATING ORNAMENTAL PLANTS
ABELIA: softwood, greenwood, semi-ripewood cuttings
ABIES: fresh seed—soak 30 hours and then moist-cold (30 days), light, sow indoors (50–60° F) (germ. 21–30 days); evergreen hardwood cuttings in mid- to late winter, hormone, bottom heat; grafting
ABUTILON: seed—sow indoors (70–75° F) (germ. 30–90 days); softwood, greenwood, semi-ripewood cuttings
ACACIA: seed—file, hot water and then 24-hour soak, then sow indoors (70–80° F) (germ. 21 days); greenwood cuttings
ACALYPHA: softwood, semi-ripe cuttings; division
ACANTHUS: seed—outdoors, or sow indoors cool (50–55° F) (germ. 21–25 days); herbaceous cuttings in autumn; division; root cuttings
ACER: fresh seed—light, outdoors in autumn, or 48-hour water soak, moist-warm (60 days) followed by moist-cold (60 days) followed by light, sow indoors (65–70° F) (germ. 30–365+ days) (note: A. rubrum, A. saccharinum, sow indoors when ripe in late spring to summer; some maples, such as A. griseum, set very few viable seeds); softwood cuttings; layering; grafting
ACHILLEA: seed—light, outdoors in spring or summer up to 2 months before frost, or light, sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 10 days); division; basal cuttings
ACHIMENES: seed—sow indoors (70–75° F) (germ. 14–21 days); herbaceous stem, leaf cuttings; rhizome (tubercle) division
ACONITUM: seed—light, outdoors in frame, or moist-cold (40 days) and then light, sow indoors (70–75° F) (germination erratic); divide early (slow to reestablish)
ACORUS: rhizome division in late spring
ACTAEA: fresh seed—outdoors in autumn, or moist-warm (90 days) followed by moist-cold (90 days) followed by sow indoors (60–70° F) (germ. 270+ days up to 2 years) (two-step germination, see here); rhizome division
ACTINIDIA: fresh (green) seed—clean of pulp, sow indoors (50° F) (germ. 7–14 days); dry seed—moist-cold (90 days) followed by sow indoors (50–60° F) (germ. 14–60 days); greenwood, semi-ripewood, hardwood cuttings; layering; grafting
ADIANTUM: spore—(70–75° F); division
ADONIS: fresh seed—outdoors; division
AECHMEA: fresh seed—clean from berries, light, sow indoors on moist sphagnum, high humidity (germ. 7–90 days) (70° F); offsets (pups)
AEONIUM: very fresh seed—some plants are monocarpic and must be raised from seed, sow indoors (65–75° F) (germ. 30–90 days); semi-ripe cuttings of side shoots; leggy, older plants can have stem and top rosette removed and be rooted as stem cutting (anytime, but spring easiest; allow all cuttings to air-dry at least 24 hours)
AESCULUS: fresh seed—outdoors (some species moist-cold 120 days); hardwood cuttings; layer shrubby kinds; grafting (budding); division of root suckers; root cuttings in winter of some species
AGAPANTHUS: seed—sow indoors (70–75° F) (germ. 30–90 days); rhizome division
AGASTACHE: seed—sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 30–120 days); herbaceous (semi-ripe) cuttings; division
AGAVE: fresh seed—light, sow indoors (70–75° F) (germ. 30–90 days); offset division
AGLAONEMA: division of suckers
AJUGA: divide and transplant plantlets with roots that form along runner (some vigorous varieties are potentially invasive, although easy to weed—keep away from lawn)
ALCEA: seed—sow in situ, or sow indoors (70–75° F) (germ. 10–21 days)
ALCHEMILLA: fresh seed—sow in situ in early spring, or sow indoors (60–70° F) 6–8 weeks before last frost date (germ. 21–30 days); division in spring or through the season with cover
ALLAMANDA: semi-ripewood cuttings
ALLIUM: fresh seed—light, outdoors in autumn for hardiest, but most outdoors in spring (store dry in refrigerator), or moist-cold (30 days), followed by light, sow indoors (50–60° F) (germ. 30–365 days); bulb offsets; bulbils
ALNUS: fresh seed—outdoors in autumn or winter; greenwood cuttings in late spring; grafting
ALOCASIA: rhizome or tuber (by species) division
ALOE: seed—light, sow indoors (70–75° F) (germ. 21–28 days); leaf cuttings; offsets
ALSTROEMERIA: fresh seed—where plants are hardy, soak in warm water, and then sow in situ 1 week before last frost or 1 week before first in mild climates, or sow indoors, keep moist (65–75° F) (germ. 15–365 days, erratic); rhizome division in autumn (difficult)
ALTERNANTHERA: seed—sow indoors (70–75° F) (germ. 1–21 days); herbaceous stem cuttings; division for hardy kinds
ALTHAEA: seed—light, sow indoors (60–70° F) 6–8 weeks before last frost date (germ. 10–14 days); division of suckers sometimes possible, or basal cuttings, but difficult
ALYSSUM: seed—light, outdoors in early spring or early autumn, or light, sow indoors (60–65° F) 8–10 weeks before last frost date (germ. 5–14 days); semi-ripe cuttings (summer)
AMARANTHUS: seed—sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 10–15 days)
AMELANCHIER: fresh seed—outdoors; stored seed, outdoors in spring to germinate following spring, or moist-warm (90 days) followed by moist-cold (90 days) then sow indoors (60–65° F) (germ. erratic); semi-ripewood cuttings; layering; division of suckers
AMORPHA: seed—12-hour warm-water soak, sow indoors (50–60° F) (germ. 30–120 days); division of suckers
AMORPHOPHALLUS: division of offset tubers
AMSONIA: seed—outdoors, or moist-cold (30–42 days)—nicking aids germination (germ. 30–365 days); herbaceous cuttings; division
ANAGALLIS: seed—annuals, sow indoors (70–75° F) (germ. 18–21 days); hardy annuals, sow in situ; perennial kinds, division of rooted layers
ANANAS: division of suckers (pups) from crown and base of fruit; cut leafy top off fruit, allow cut surface to dry 24 hours, root on medium
ANAPHALIS: seed—outdoors, or sow indoors (55–65° F) 6–8 weeks before last frost date (germ. 30–60 days); division; basal cuttings
ANCHUSA: seeds—sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 7–30 days); division; root cuttings
ANDROMEDA: seed—light, sow indoors (50–60° F; note: keep pot in saucer of water to maintain high moisture) (germ. 30–60 days)
ANEMONE: seed—species, outdoors in autumn (or spring) to germinate following spring; division in spring; root cuttings in winter (A. blanda, division of corms when leaves die down in late spring)
ANEMONELLA: fresh seed—outdoors in summer; division (necessary for double form)
ANGELICA: fresh seed—in situ or moist-cold (14 days) then light, sow indoors (60–70° F) (germ. 20–60 days)
ANTENNARIA: seed—sow indoors (70–75° F) (germ. 30–70 days); spring or autumn division of basal offsets
ANTHEMIS: seed—sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 7–21 days); herbaceous stem cuttings; division in spring; basal stem cuttings of alpine types
ANTHURIUM: fresh seed—sow indoors (75–80° F with high humidity) (germ. 2–30 days); division of offsets with roots
ANTIRRHINUM: seed—light, sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 7–14 days); herbaceous stem cuttings (spring), semi-ripe cuttings (autumn)
AQUILEGIA: seed—light, sow in situ, or moist-cold (21 days), light, sow indoors (70–75° F) (germ. 21–28 days); division of basal growths for rooting in warm climates or in greenhouse or frame
ARABIS: seed—light, sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 21–28 days); herbaceous cuttings after flowering; division of rooted layers of creeping forms
ARALIA: seed—outdoors, or moist-warm (90 days) followed by moist-cold (90 days) and then sow indoors (70–75° F) (germ. 21 days); division of suckers (splice side graft); dormant root cuttings
ARAUCARIA: fresh seed—moist-cold (21–84 days) and then dark, sow indoors (55–60° F) (germ. 14–60 days [hypogeal germination—seed leaves remain below surface as true leaves emerge]); semi-ripewood cuttings
ARBUTUS: seed—moist-cold (60–90 days) followed by light, sow indoors (65–70° F) (germ. 30–120 days); semi-ripewood cuttings; layering; grafting
ARCTOSTAPHYLOS: semi-ripewood cuttings—mist helpful (A. uva-ursi, layering as well)
ARCTOTIS: seed—sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 14–21 days); herbaceous cuttings in autumn
ARDISIA: seed—mash pulp and place in water to ferment for 14 days and then rinse, dry, soak (24 hours) followed by sow indoors (70–75° F) (germ. 7–21 days); softwood, semi-ripewood cuttings
ARENARIA: seed—light, sow indoors (55° F) 6–8 weeks before last frost date (germ. 7–30 days); cuttings; division of rooted layers of creeping forms
ARGEMONE: seed—in situ after last frost (germ. 14 days)
ARISAEMA: fresh seed—moist-cold (45 days), then light, sow indoors (55–60° F) (germ. 14–21 days [although easy from freshly cleaned seed, may be difficult from dried seed, which should be soaked before sowing, and may take up to 180 days to germinate]); removal of offset tubers from around parent tubers in spring in cold climates, autumn in warm climates
ARISARUM: fresh seed—moist-cold (45 days), then sow indoors (60–70° F) (germ. 14–21 days); tuber division
ARISTOLOCHIA: seed hardy kinds: outdoors in spring, or moist-cold (90 days)—tender kinds: soak in warm water 48 hours—followed by sow indoors (65–70° F) (germ. variable by type); softwood (tender species and varieties only), greenwood, semi-hardwood cuttings; division
ARMERIA: seed—soak in warm water 6–8 hours, sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 10–21 days); division
ARMORACIA: division; root cuttings
ARONIA: softwood, greenwood cuttings; layering; division of suckers
ARTEMISIA: seed—light, outdoors, or light, sow indoors (60–65° F) 10–12 weeks before last frost date (germ. 30–180 days); greenwood stem-tip cuttings, semi-ripe stem-tip cuttings (keep foliage dry or cuttings may rot); division; basal cuttings (less hardy kinds can be taken to overwinter in cold frame)
ARUM: fresh seed—moist-cold (45 days) and then sow indoors (55–65° F) 10–12 weeks before planting out in spring or autumn (germ. 14–21 days); tuber division
ARUNCUS: fresh seed—light, outdoors after last frost, or light, sow indoors (70–75° F) (old seed must be soaked and moist-cold 30–90 days) (germ. 30–90 days); division
ARUNDO: division in spring
ASARINA: seed—light, sow indoors (70–75° F) 10–12 weeks before last frost date (germ. 14–30 days); stem-tip cuttings
ASARUM: fresh seed—outdoors as soon as seed is ripe, or moist-cold (30 days) followed by sow indoors (60–65° F) (germ. 7–21 days); rhizomatous stem division in spring (early autumn for hardiest kinds)
ASCLEPIAS: fresh seed—tender and annual kinds: sow indoors (70–75° F) (germ. 21–28 days); hardy kinds: outdoors, or moist-cold (21 days) and then sow indoors (70–75° F) (germ. 30–90 days); herbaceous cuttings; root cuttings
ASIMINA: fresh seed—moist-cold (60–90 days; radicle forms during moist-cold) (germ. 90–150 days); root cuttings in winter
ASPARAGUS: fresh seed (tender ornamentals)—soak 24 hours, sow indoors (70–75° F) (germ. 28 days); division; tuber division
ASPIDISTRA: division
ASPLENIUM: spores—(70–75° F); division; root “bulbils” (adventitious plantlets) while still attached to fronds by pinning to medium
ASTER: seed—outdoors, or sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 15–20 days [may benefit from moist-cold 14 days]); herbaceous cuttings in spring; division; basal cuttings
ASTILBE: (species) fresh seed—moist-warm (14 days) and then moist-cold (28 days), sow indoors (60–70° F) 6–8 weeks before last frost date (germ. 21–60 days); division in spring
ASTILBOIDES: seed—sow indoors (70–75° F) (germ. 7–14 days); division
ASTRANTIA: seed—light, outdoors when ripe; selections by division in spring or autumn
ATHYRIUM: spores—(70–75° F); division; root “bulbils” (adventitious plantlets) while still attached to fronds by pinning to medium
ATRIPLEX: seed—outdoors after last frost but while soil still cool
AUBRIETA: seed—light, sow indoors (65–70° F) 6–8 weeks before last frost date (germ. 14–21 days); semi-ripe cuttings in summer; division in early spring
AUCUBA: fresh seed—rub pulp from seeds, outdoors (germ. 540 days), or sow indoors (65–70° F) (germ. 30–90 days); semi-ripewood cuttings (cold frame); layering
AURINIA: seed—light, outdoors in early spring or early autumn, or light, sow indoors (60–65° F) 8–10 weeks before last frost date (germ. 5 –21 days); herbaceous cuttings in spring, semi-ripe cuttings in summer to late summer; division in autumn
BABIANA: seed—sow indoors (70–75° F) (germ. 28–56 days)
BACCHARIS: fresh seed—sow indoors (70–75° F) (germ. 7–14 days)
BAPTISIA: fresh seed (just-ripe seed), sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 7–35 days); stored seed must be nicked followed by sow indoors (70–75° F); division
BEGONIA: seed—light, sow indoors (70–75° F) 3–4 months before last frost date for bedding types and tuberous varieties (seed must be on surface) (germ. 14–60 days); by type: herbaceous cuttings anytime (stem, leaf); rhizome cuttings; tuberous: sections of tuber as shoots appear; bulbils in leaf axils of some; shoots with bit of tuber treated as stem cuttings; basal stem cuttings in summer
BELAMCANDA: seed—sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 14–21 days); division in spring
BELLIS: seed—light, sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 1–15 days), in cold frame in late summer for spring bloom; divide special cultivars after flowering
BERBERIS: seed—light, outdoors, or moist-cold (60 days) followed by light, sow indoors (50–65° F) (germ. 60–180 days); softwood, semi-ripewood mallet cuttings (see here); semi-ripewood cuttings; grafting; division
BERGENIA: seed—outdoors, or moist-cold (14 days) followed by sow indoors (60–70° F) 6–8 weeks before last frost date (germ. 30–80 days); rhizome cuttings in late winter (bury half deep in perlite with bottom heat); division in spring
BETULA: fresh seed—light, outdoors (if planted as soon as ripe, germination may be immediate), or moist-cold (70 days) followed by light, sow indoors (65–75° F) (germ. 30–90 days); greenwood, semi-ripewood cuttings with mist (difficult); grafting
BIGNONIA: seed—outdoors; semi-ripewood cuttings; layering
BLECHNUM: spores—(70–75° F); offsets from stolons (rhizomes)
BOLTONIA: seed—outdoors, or sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 14–21 days); herbaceous cuttings; division; basal cuttings
BOUGAINVILLEA: softwood, semi-ripewood (bottom heat), hardwood cuttings; layering
BOWIEA: scale seedings; division of offsets
BRACHYCOME: seeds—sow indoors (70–75° F) 6–8 weeks before last frost date (70° F) (germ. 14–21 days); basal cuttings
BRIZA: seed—sow indoors (55° F) 6–8 weeks before last frost date (germ. 1–14 days); division of perennial types
BRODIAEA: seed—sow indoors (55–60° F) (germ. 30–90 days); division of cormels in autumn
BROUSSONETIA: seed—outdoors; softwood cuttings
BROWALLIA: seed—light, sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 14–21 days); herbaceous cuttings
BRUGMANSIA: seed—light, sow indoors (70–75° F) (germ. 21–60 days); softwood, greenwood, semi-ripewood cuttings
BRUNFELSIA: softwood, greenwood cuttings
BRUNNERA: seed—moist-cold (30 days) and then sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 30–90 days), or outdoors in late summer to autumn for cold frame; division; root cuttings in late winter in greenhouse
BUDDLEIA: seed—light, outdoors, or moist-cold (30 days) followed by light, sow indoors (70–75° F) (germ. 20–30 days); softwood, greenwood, semi-ripewood, hardwood cuttings
BULBOCODIUM: seed—outdoors; division after flowering and plants are dormant
BUPLEURUM: seed—sow indoors (70–75° F) (germ. 14–28 days); semi-ripewood cuttings; division in warm climates
BUTOMUS: fresh seed—sow indoors cool (55–65° F), keep medium saturated in bowl of water (germ. 30–60 days, erratic); division in spring; bulbils
BUXUS: seed—outdoors in spring; greenwood, semi-ripewood cuttings
CALADIUM: fresh seed—sow indoors (70–75° F) immediately (germ. 30–90 days); varieties can only be propagated vegetatively; division of tuber offsets; sections of tubers in spring
CALAMINTHA: seed—outdoors in situ when soil warm, or sow indoors (60–70° F) 8–10 weeks before last frost date (germ. 7–14 days); herbaceous stem cuttings in spring; division in spring; transplant self-layered plantlets
CALANTHE: divide rhizome sections with at least two pseudobulbs and growing shoot in early spring
CALATHEA: semi-ripe cuttings; division
CALCEOLARIA: seed—light, sow indoors in autumn (70–75° F) (germ. 5–10 days), keep cool after germination (50–55° F at night)
CALENDULA: seed—dark, outdoors in spring when still cool and frost possible, or dark, sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 1–14 days)
CALLICARPA: seed—clean of pulp, light, sow indoors (70° F) (germ. 7–14 days), outdoors in autumn, or dried in spring; semi-ripewood, hardwood cuttings
CALLIRHOE: seed—light, outdoors where hardy, or light, sow indoors (50–60° F) (germ. 30–180 days); stem-tip or semi-ripe cuttings of some kinds
CALLISTEMON: seed—light, sow indoors (55–65° F) (germ. 14–60 days); greenwood, semi-ripewood cuttings
CALLUNA: fresh seed—light, outdoors, or moist-cold (30 days) followed by light, sow indoors (65–70° F) (germ. 30–60 days); small softwood cuttings
CALTHA: fresh seed—outdoors best, or sow indoors (55–60° F) (germ. 30–90 days); division in spring after flowering or in late summer
CALYCANTHUS: seed—outdoors in autumn; greenwood, semi-ripewood cuttings; division of suckers
CAMASSIA: seed—sow indoors cool (55– 60° F) (germ. 30–180 days); division of offsets in autumn
CAMELLIA: seed—soak in warm water 24–48 hours, sow indoors (70–75° F) (germ. 30–60 days) (may be difficult, try moist-cold 30–60 days); semi-ripewood cuttings (nodal, internodal stem-tip, and leaf cuttings [leaf-bud, split leaf bud] as per evergreen rhododendrons); layering; grafting
CAMPANULA: seed—light, sow indoors (70–75° F) 8–10 weeks before setting out while still cool and light frosts possible (germ. 14–28 days); division in spring; basal stem cuttings; root cuttings of some species
CAMPSIS: seed—moist-cold (60 days) followed by light, sow indoors (70–75° F) (germ. 14–21 days)
CANNA: seed—scarification and soak in warm water 48 hours, sow indoors (70–75° F) (germ. 7–14 [or up to 365] days); rhizome cuttings; division of suckers from base and cutting off rhizome bud nodules (toes) that form on some kinds of cannas
CARAGANA: seed—24–48-hour soak in warm water followed by light, outdoors, or light, sow indoors (65–70° F) (germ. 14–21 days); greenwood cuttings
CARDAMINE (DENTARIA): fresh seed—outdoors, or sow indoors immediately to grow cool; herbaceous cuttings in late spring (leaf cuttings of C. pratensis); division of rhizomes
CARDIOCRINUM: seed—outdoors where temperature does not drop below 15° F, or (two-step germinator, see here) moist-warm followed by moist-cold and sow indoors (70–75° F) (germ. 90–700 days); division of offsets (plant is monocarpic)
CAREX: fresh seed—light, sow indoors (70–75° F) (germ. varies by species, 7–60 days); division
CARPINUS: fresh seed—light, outdoors, or if seed has dried, scarify followed by moist-warm (30 days) followed by moist-cold (120 days) and then light, sow indoors (60–70° F) (germ. 30–365 days); greenwood cuttings; grafting (whip)
CARYOPTERIS: seed—sow indoors (65–70° F) (germ. 30–90 days); softwood, green-wood, semi-ripewood, hardwood cuttings
CASSIA: seed—hardy herbaceous perennial: scarification followed by sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 7–90 days); stem cuttings; division in spring
CATALPA: seed—light, sow indoors (60–70° F) (germ. 14–30 days; note: stored seed germinates readily); greenwood cuttings with heel; grafting (chip-budding); root cuttings
CATANANCHE: seed—sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 14–21 days); division when in active growth; root cuttings in winter
CATHARANTHUS: seed—dark, sow indoors (70–75° F) 12–14 weeks before any possible frost danger has passed (germ. 14–21 days); semi-ripe cuttings in late summer to early autumn
CATTLEYA: division of pseudobulbs
CAULOPHYLLUM: division in spring or early autumn; sections of rhizome
CEANOTHUS: seed—24-hour soak followed moist-cold (14 days) and then light, sow indoors (65–70° F) (germ. 30–60 days); softwood, semi-ripewood, hardwood cuttings; root cuttings in autumn
CEDRUS: fresh seed—germinates readily (3-hour soak followed by moist-cold, 14 days, helpful), light, sow indoors (60–65° F) (germ. 7–60 days, erratic); evergreen hardwood cuttings (in October or later, hormone and bottom heat); grafting (to C. deodara)
CELOSIA: seed—light, sow indoors (70–75° F) (germ. 7–14 days)
CENTAUREA: seed—(annuals in situ); dark, sow indoors (60–70° F) 6–8 weeks before last frost date (germ. 7–30 days); (perennials: division in spring; root cuttings in winter)
CENTRANTHUS: fresh seed—outdoors, or sow indoors (60–70° F) 8 weeks before last frost date (germ. 21–30 days); division in spring
CEPHALANTHUS: seed—outdoors in autumn, or sow indoors (70–75° F) (germ. 7–14 days); semi-ripewood, hardwood cuttings
CEPHALARIA: seed—outdoors, or moist-cold (40 days) followed by sow indoors (55– 65° F) (germ. 21–60 days); basal stem cuttings in midspring
CEPHALOTAXUS: seed—(recommendations vary; my attempt with only cold stratification failed) outdoors, or moist-cold (90 days) followed by moist-warm (90 days) followed by moist-cold (90 days), sow indoors (60–65° F); semi-ripewood cuttings (hormone, wounding perhaps, helps—mist accelerates rooting); grafting
CERASTIUM: seed—sow indoors (65–75° F) 6–8 weeks before last frost date (germ. 5–10 days); herbaceous stem-tip cuttings spring; division in spring
CERATOSTIGMA: seed—moist-cold (40 days) prior to sow indoors (60° F) (germ. 30–90 days); softwood cuttings; division; root cuttings
CERCIDIPHYLLUM: fresh seed—sow indoors (70–75° F) (germ. 7–14 days) (note: store clean and dry seed in refrigerator followed by above)
CERCIS: seed—hot water (170° F) and then 24-hour soak followed by light, outdoors, or moist-cold (6–90 days) and then light, sow indoors (70–75° F) (germ. 30–90 days); greenwood cuttings; grafting (apical-wedge)
CEROPEGIA: seed—sow indoors (75–90° F) (germ. quickly, fresh seed in less than a week); stem cuttings, runners while attached in daughter pots; division of tubers; tubercles
CESTRUM: seed—light, sow indoors (70–75° F) (germ. 70 days); softwood, greenwood, semi-ripewood cuttings
CHAENOMELES: fresh seed—pick seeds out of cut fruit and then light, outdoors, or moist-cold (60–70 weeks) followed by light, sow indoors (55–65° F) (germ. 70–90 days); softwood, greenwood, hardwood cuttings; layering (mounding); root cuttings
CHAMAECYPARIS: seed—harvest in autumn and store moist-cold (60 days) followed by light, sow indoors (50–60° F) (germ. 30–60 days); evergreen hardwood cuttings in late summer to midautumn; grafting
CHAMAEDOREA: seed—soak 24–48 hours, sow indoors (70–75° F) (germ. 30–120 days); offsets
CHASMANTHIUM: seed—light, outdoors; division; basal offsets
CHEILANTHES: spores; division of rhizomes
CHELONE: seed—moist-cold (40 days) followed by sow indoors (55–65° F) (germ. 14 days); stem cuttings in late spring; division in spring
CHIMONANTHUS: fresh seed—when fruits are green, light, sow indoors (70–75° F) (germ. 60 days), or ripe and stored seed, moist-cold (90 days) followed by moist-warm (90 days), sow indoors (germ. 60–90 days); softwood cuttings (heel); layering
CHIONANTHUS: seed—light, outdoors (germ. 2 years), or moist-cold (30 days) followed by light, sow indoors (60–70° F) (germ. 30–180 days or longer [note: germ. may not occur until second spring]); alternative method for seed—moist-warm (90 days) followed by moist-cold (90 days), light, sow indoors (60–70° F); layering
CHIONODOXA: fresh seed—outdoors in situ, or sow indoors (50° F) (germ. 30–90 days); division of offsets in autumn
CHLOROPHYTUM: division; peg offsets to medium while attached to parent (daughter pot), or separate and root in medium
CHOISYA: semi-ripewood cuttings, mist helpful
CHRYSANTHEMUM: seed—sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 1–21 days), perennial species appreciate lower temperatures at night; stem cuttings (bottom heat helpful) anytime—easiest in spring—(overwinter in cold frame); division in spring
CHRYSOGONUM: fresh seed—outdoors, or sow indoors (60–70° F) (germ. 21–30 days); division in spring
CIMICIFUGA: fresh seed—outdoors, or moist-cold (60–380 days), or sow indoors (55–60° F) (germ. slow—90–380 days); division in spring (best) or autumn (apply loose mulch)
CISSUS: seed—sow indoors (70–75° F) (germ. 30–180 days); tender species—stem cuttings (bottom heat helpful) in spring; hardy kinds—semi-ripewood to semi-ripewood cuttings (mist helpful); layering
CISTUS: seed—light, sow indoors (65–70° F; medium must be very moist at all times, cover pot with pane of glass, or pre-germinate on moist paper towel in plastic bag) (germ. 7–30 days); softwood to semi-ripewood cuttings
CITRUS: semi-ripe cuttings in summer (hormone and mist helpful); grafting; air layering
CLADRASTIS: seed—dry-stored should be steeped in warm water (120° F—gas oven with pilot light, perhaps—replenish water a few times) 2–3 days until swollen and sow indoors (70–75° F) (germ. 14–21 days); root cuttings
CLAYTONIA: fresh seed—collect ripe seed and sow immediately outdoors
CLEMATIS: seed—moist-cold (2–6 months depending on species), sow indoors (70–75° F) (germ. 30–365 days depending on species); cuttings variable by type, include softwood and semi-ripe leaf-bud cuttings, semi-ripewood stem cuttings; layering (serpentine, see here); specialized grafting onto C. vitalba seedling understock
CLEOME: seed—8–10 weeks before last frost date, moist-cold (14 days) and then light, sow indoors (70–75° F) (germ. 1–14 days), or sow in situ in spring
CLERODENDRUM: seed—hardy species, moist-cold (30–90 days) followed by light, sow indoors (65–70° F) (germ. 30–90 days); softwood, semi-ripewood cuttings; division; root cuttings
CLETHRA: fresh seed—moist-cold (90 days) followed by moist-warm (90 days), light, sow indoors (70° F) with high humidity or even under mist (germ. 21 days); greenwood cuttings (softwood and semi-ripewood cuttings of evergreen varieties possible under mist); layering; division of suckers
CLINTONIA: fresh seed—outdoors, or sow indoors in late winter (55–60° F) (germ. 30–90 days), cold frame first winter; division
CLIVIA: fresh seed—sow indoors (70– 80° F) (germ. 7–21 days, dry-stored seed takes longer); division of offsets
COBAEA: seed—sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 14–30 days); semi-ripe cuttings
CODONOPSIS: fresh seed—light, sow indoors (60–70° F) (germ. 7–42 days)
COFFEA: seed—soak in warm water 48 hours followed by light, sow indoors (70–75° F) (germ. erratic—42 days or longer); semi-ripewood cuttings under mist with bottom heat
COLCHICUM: seed—outdoors; divide cormels during summer
COLEUS (SOLENOSTEMON): seed—light, sow indoors (70–75° F) 8–12 weeks before last frost date (germ. 1–15 days); stem cuttings (bottom heat helpful) anytime, but fastest in late winter to early summer
COLOCASIA: in late winter to spring, cut sections of tuber to include at least one eye, allow divisions to air-dry for several days before planting; division of tuber offsets with eyes; basal stem cuttings with section of tuber
COLUMNEA: seed—light, sow indoors (70–75° F) (germ. 30–300 days); stem cuttings (bottom heat helpful) anytime
COMPTONIA: (propagation difficult) division—separation of good-size plants—from suckers; root cuttings in late winter to early spring
CONSOLIDA: seed—dark, sow in situ in late winter to spring
CONVALLARIA: fresh seed—light, outdoors; division of rhizomes (pips)
CORDYLINE: seed—soak hot water, sow indoors (70–75° F) (germ. 30–90 days); stem-section cuttings; air layering
COREOPSIS: seed—light, sow indoors (annuals: 6–8 weeks before last frost date, 70–75° F; perennials: 8–10 weeks before last frost date, 55–70° F) (germ. 2–25 days); perennial kinds: division; basal stem cuttings in spring
CORNUS: seed—light, outdoors, or moist-warm (60 days) followed by moist-cold (90 days) and then light, sow indoors (50–60° F) (germ. 90–730 days); shrubby species: softwood, greenwood, semi-ripewood cuttings with mist, or hardwood cuttings (often easiest); tree types (difficult): softwood cuttings under mist (note: do not remove cuttings from medium once rooted; devote a flat to the cuttings and allow them to go through winter dormancy before repotting [try Oasis or rock wool blocks]); grafting; division of suckers from shrub types
CORYDALIS: fresh seed—light, best sown in situ (it is easy to germinate seeds indoors, but seedlings have long taproots that are easily damaged—consider paper pots, light [50–60° F] [germ. 30–60 days]); rhizome-forming species: division in autumn or early spring while dormant
CORYLOPSIS: seed—outdoors (2 years), or moist-warm (6 months) followed by moist-cold (6 months); softwood cuttings (wound, see here—Oasis cubes or rock wool may be helpful); layering; grafting
CORYLUS: fresh seed—moist-cold (90 days), or seed stored dry up to a year, (70° F) (germ. 30 days); softwood stem cuttings under mist very successful (note: do not remove from medium once rooted—set in pots of medium or devote a flat to these and allow cuttings to go through winter dormancy before repotting); layering, including stooling or mounding
COSMOS: seed—outdoors after danger of frost is past, or sow indoors (70–75° F) 4–5 weeks before last frost (germ. 5–10 days)
COTINUS: fresh (near-ripe “green”) seed—outdoors (dry-stored seed difficult: nick and 12-hour soak followed by moist-cold [42–63 days] and then sow indoors [55–60° F] [germ. 30–90 days]—or moist-warm [180– 270 days] followed by moist-cold [6–9 months]); softwood cuttings (hormone necessary) (note: do not remove from medium once rooted—try Oasis cubes, or devote a flat to these and allow cuttings to go through winter dormancy before repotting, or set a pot of rooting medium into a larger container of potting medium and overwinter in cold frame); layering in late winter to early spring (easiest method)
COTONEASTER: seed—clean of pulp, often acid-etched (sulfuric acid etch may be replaced by stratification), moist-warm (120–270 days) followed by moist-cold (90 days) and then light, sow indoors warm (70° F) (germ. 180–365 days), or outdoors in spring; softwood, greenwood cuttings (semi-ripewood cuttings with hormone in cold frame); layering; grafting
COTULA: seed—sow indoors (50° F) 6–8 weeks before last frost date, or outdoors after danger of frost is past (germ. 14–42 days); division of perennial kinds in spring
CRAMBE: fresh seed—best sown in situ, or sow indoors cold (40° F) (germ. 21–180 days); division; root cuttings (material should be heavy—pencil-thick)
CRASSULA: stem or leaf cuttings (allow to callus at least 24 hours)
CRATAEGUS: seed—acid-etch nearly impenetrable seed coat followed by moist-cold (90 days) (germ. 60+ days); or as substitute for acid, moist-warm (120–270 days) followed by moist-cold (90 days) and then light, sow indoors cool (50–65° F) (germ. 180–730 days); grafting (budding); root cuttings in early spring may work
CRINUM: fresh seed—outdoors in warm climates, or sow indoors (60–70° F) 6–8 weeks before last frost date (germ. 7–21 days); division of offsets from bulbs in spring
CROCOSMIA: fresh seed—sow indoors (55–60° F) 6–8 weeks before last frost date (germ. 60–90 days); division of thick mats—saving cormels and discarding oldest corms in early spring or after flowering; sections of corms
CROCUS: fresh seed—outdoors in spring (germ. 30–180 days); division of corms
CRYPTOMERIA: seed—store seeds dry, then moist-cold (21 days) and sow indoors with gentle bottom heat (65° F) (germ. 30–60 days—erratic); semi-ripewood cuttings; grafting
CUPHEA: seed—light, sow indoors (70–75° F) 10–12 weeks before last frost date (germ. 8–10 days) (note: plants used as summer annuals take a long time to develop, so early indoor sowing is recommended); herbaceous stem cuttings; root cuttings
CUPRESSUS: seed—light, outdoors in late winter or early spring, or moist-cold (30 days) followed by light, sow indoors (70–75° F) (germ. 30–90 days—erratic); evergreen-hardwood cuttings in late winter to early spring, hormone and mist; grafting
CYCAS: seed—(fresh if possible), sow indoors (70–75° F) (germ. 30–90 days or longer); division of offsets
CYCLAMEN: seed—dark, sow indoors (50–60° F) (germ. 21–180 days); hardy species may be sown outdoors following hot-water soak in autumn or spring, moist-cold (21 days) and then dark, sow indoors, shade and high humidity as seedlings emerge; corms can be divided in late summer, but seed is preferable
CYDONIA: seed—as Chaenomeles, varieties are all grafts onto species seedling (whip-and-tongue, chip-bud, T-bud)
CYMBALARIA: seed—outdoors in rock crevices anytime when seed is available (spring to late summer)
CYMBIDIUM: divisions of pseudobulbs; rooting “backbulbs”—aged pseudobulbs that can be removed and rooted in medium to produce shoots
CYNARA: seed—sow indoors (50–55° F) (germ. 14–30 days); division in early spring, but seed preferable
CYNOGLOSSUM: seed—cover seeds in situ in spring, or dark, sow indoors (70–75° F) (germ. 5–10 days); division in spring where hardy
CYPERUS: seed—sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 25–30 days); leaf-petiole (rosette) cuttings (cut entire leaf umbel with 1-inch stem—peg to medium or float on water); division
CYPHOMANDRA: seed—sow indoors (70–75° F) (germ. 20–25 days); softwood cuttings
CYRILLA: fresh seed—outdoors; semi-ripewood cuttings, hormone; root cuttings
CYTISUS: seed—hot-water soak followed by light, sow indoors (70–75° F) (germ. 25–30 days); semi-ripewood (side shoot with heel, hormone), hardwood (hormone) cuttings
DAHLIA: seed—sow indoors (70–75° F) 10–12 weeks before last frost date (germ. 5–10 days); stem cuttings (bottom heat helpful); spring tuber division with at least one eye
DAPHNE: fresh seed—clean of pulp, light, sow indoors (50–60° F) (germ. 150–365 days), or in frost-free place, cold frame perhaps; stem cuttings vary by species: green-wood and semi-ripewood nodal stem cuttings (note: do not remove cuttings from medium once rooted—devote a flat to these and allow cuttings to go through winter dormancy before repotting [try Oasis or rock wool blocks]; with bottom heat, roots may form in 6 weeks; cuttings that lose their leaves before rooting should be discarded); layering; grafting (splice veneer, whip-and-tongue, wedge); root cuttings
DARMERA: seed—sow indoors (55–60° F) (germ. 30–90 days); division in spring
DATURA: seed—sow indoors (55–65° F) 8–12 weeks before last frost date (germ. 21–42 days); softwood cuttings (from side shoots)
DAVALLIA: spores; rhizome sections pinned or pegged to medium, bottom heat
DAVIDIA: fresh seed—clean (two-step germinator, see here), moist-warm (90 days or until emergence of radicle) then pot up and refrigerate (90 days); softwood (wounding and hormone), leaf-bud cuttings best (use hormone and try Oasis cubes as all resent transplanting)
DELOSPERMA: seed—light, sow indoors (70–75° F) (germ. 1–40 days)
DELPHINIUM (SEE ALSO CONSOLIDA): fresh seed—dark, sow indoors (50–55° F) 8–10 weeks before last frost date (germ. 14–28 days), or outdoors in spring to late summer in time to germinate before frost; division in spring; basal cuttings in spring (take cuttings low at base of plant so hollow stems are closed)
DENDROBIUM: stem cuttings laid horizontally on medium; division of plantlets
DENNSTAEDTIA: spores; division of rhizomes in spring
DENTARIA: see Cardamine
DESCHAMPSIA: seed—light, outdoors; division in spring or autumn
DEUTZIA: seed—outdoors, or moist-cold helpful (42–56 days), sow indoors (65–70° F) (germ. 30–60 days); stem cuttings easy—softwood, greenwood, semi-ripewood, hardwood
DIANTHUS: Annual varieties: seed—sow indoors (60–70° F) 8–10 weeks before last frost date (germ. 5–10 days); semi-ripe cuttings. Biennials, such as sweet William: seed—outdoors in spring to summer for blossoms the following year, or sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 10 days) 42–60 days before setting out; root cuttings. Perennials: seed—sow indoors (under lights, 60–70° F; or outdoors after danger of frost is past) 8–10 weeks before last frost date (germ. 10 days); semi-ripe cuttings; division in spring
DICENTRA: fresh seed—outdoors, or if not fresh, dry-stored seed requires moist-warm (6 weeks), moist-cold (6 weeks), moist-warm (6 weeks) followed by sow indoors (55–60° F) (germ. 30 days or longer); division in late winter to early spring; root cuttings in summer. Note: Asian D. spec-tabilis germinates following moist-cold (6 weeks) followed by sow indoors (50–55° F); and also yields stem cuttings after flowering
DICTAMNUS: seed—outdoors, or moist-cold (42 days) followed by sow indoors (55– 60° F) (germ. 30–180 days); division possible, but plants resent disturbance; root cuttings of dormant plants
DIERAMA: seed—light, outdoors in warm climates, in autumn or spring, or light, sow indoors (60–65° F) (germ. 30–180 days); division of cormels
DIGITALIS: seed—light, outdoors in spring through summer, or light, sow indoors cool (60–70° F) 8–10 weeks before last frost date (germ. 10–20 days); division of basal rosettes in spring (or autumn in warm climates)
DISPORUM: seed—light, outdoors, or moist-cold (42 days) followed by light, sow indoors cool (55–65° F) (germ. 30–180 days or longer); division easy in spring
DODECATHEON: seed—outdoors in late autumn, or moist-cold ([some sources recommend freezing] 21 days) and sow indoors (60–70° F) (germ. 90–365 days); division of side rosettes in autumn
DOLICHOS: seed—soak 24 hours, sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 14 days)
DORONICUM: seed—light, sow indoors (70° F) (germ. 15–20 days); division after flowering (late summer to autumn in mild climates, mulch)
DRABA: seed—outdoors in spring, or sow indoors (55–70° F) 8–10 weeks before last frost date (germ. 30–90 days); division in spring
DRACAENA: seed—clean seeds of flesh, light, sow indoors (70–80° F) (germ. 30–42 days); stem-tip cuttings, semi-ripe sections of stem; air layering
DRYOPTERIS: spores; division
ECHEVERIA: seed—light, sow indoors (70–75° F) (germ. 15–30 days); semi-ripe stem cuttings, leaf cuttings, leggy older plants can have stem and top rosette removed and rooted as stem cutting
ECHINACEA: seed—outdoors in spring to late summer, or sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 10–21 days); division in spring easy from root cuttings in late winter
ECHINOPS: seed—outdoors in spring to midsummer, or sow indoors (60–70° F) 2–3 weeks before last frost date (germ. 15–60 days); division in spring; fast from root cuttings taken in spring
ECHIUM: seed—sow in situ (in autumn in warm climates), or sow indoors (60–70° F) 6–8 weeks before last frost date (germ. 7–21 days); stem cuttings
ELYMUS: division in spring or autumn
ENKIANTHUS: seed—light, sow indoors (70–75° F; under mist—high humidity necessary) (germ. 14–21 days); softwood, greenwood cuttings under mist very successful—do not remove from medium once rooted, set in pots of medium or devote a flat to these and allow cuttings to go through winter dormancy before repotting
EPIMEDIUM: seed—outdoors; division in spring in cold climates and in autumn in mild climates; rhizome sections can be taken and rooted on medium in winter
EPIPACTIS: division of rhizomes while dormant in early spring
EPIPHYLLUM: flat stem cuttings (see here), branches or sections
EPISCIA: as for Saintpaulia.
ERANTHIS: fresh seed—outdoors (germ. erratic, 30–365 days); division of tubers immediately after flowering
EREMURUS: seed—light, sow indoors (55–65° F) (germ. 30–365 days); division in summer or autumn (note: carefully dig and transplant sections of crown with eyes, spread roots—place on sand in poorly drained sites)
ERICA: seed—light, sow indoors warm (60–70° F) (30–120 days); softwood, semi-ripewood cuttings (two cuttings per 4-inch stem, pinch flower buds from tip, strip needles, no side shoots); layering, mounding
ERIGERON: seed—outdoors, or sow indoors (55° F) 8–10 weeks before last frost date (germ. 15–20 days); cuttings in spring; division in autumn
ERODIUM: fresh seed—in cold frame or outdoors in mild climates; semi-ripe tip cuttings; division; basal cuttings in spring; root cuttings in late winter
ERYNGIUM: seed—light, sow in situ in spring through summer, or light, sow indoors (70–75° F) (germ. 5–10 days [some take longer—may need 30 days moist-warm followed by moist-cold]); division possible but difficult due to taproot; thick root cuttings in autumn (lay horizontally on medium and just cover) (note: material for root cuttings can be encouraged by potting plants in containers with large drainage holes and setting the pots about 1 inch into a 3- to 6-inch-deep bed of moist sand—roots will grow into the medium)
ERYSIMUM: seed—biennial kinds, outdoors in late summer, or sow indoors (55– 65° F) (germ. 7 days); semi-ripe stem-tip cuttings (overwinter in cold frame); established perennials can be divided in spring
ERYTHRONIUM: fresh seed—outdoors, germination may take 9 months or longer; division of corm offsets
ESCHSCHOLZIA: seed—in situ in winter, or sow indoors (70–75° F) 2–3 weeks before last frost date (germ. 14 days)
EUCALYPTUS: seed—sow indoors (70–75° F) (germ. 14–90 days depending on species) (note: 4-week moist-cold might be helpful, as is a 10° F temperature drop at night)
EUCOMIS: seed—sow indoors (70–75° F) (germ. 20–25 days); easy from leaf cuttings; division
EUONYMUS: Species require individual treatments (most kinds offered at nurseries are varieties—vegetatively propagated). General: seed—moist-cold (3 months) followed by sow indoors (70–75° F). Deciduous varieties: softwood, greenwood, semi-ripewood (in cold frame) cuttings. Evergreen varieties: (note adventitious roots) softwood, semi-ripewood (in cold frame) cuttings. (Note: greenwood and semi-ripewood cuttings may take 6 months or more to root, hormone useful.) Layering; grafting
EUPATORIUM: seed—outdoors in autumn as seed ripens, or moist-cold (30–42 days) and sow indoors (55° F) 8–10 weeks before last frost date (germ. 30–90 days); stem cuttings in spring; divide established clumps in spring or autumn (mulch)
EUPHORBIA: Seed—tender kinds: sow indoors (70–75° F) (6–8 weeks before last frost date for garden annuals) (germ. 10– 15 days); hardy species: moist-cold (30–42 days) followed by cool to sow indoors (65–70° F) (germ. 15–30 days [may take longer]). Tender species: semi-ripewood cuttings—allow cut end to callus for 1 to 2 days before setting in medium; bottom heat helpful. Hardy species: greenwood cuttings (bottom heat helpful in areas with cool summers); division of established hardy perennials
EXACUM: seed—light, sow indoors (70–75° F) (germ. 15–20 days)
EXOCHORDA: seeds—outdoors in autumn; softwood cuttings, semi-ripewood cuttings with hormone
FAGUS: fresh seed—light, outdoors immediately, or store in refrigerator (dry) until winter and light, sow indoors (50° F) (germ. 30–365 days); cuttings nearly impossible, but sometimes layering possible; grafting
X FATSHEDERA: semi-ripewood stem cuttings (bottom heat helpful); grafting of Hedera to top
FATSIA: seed—sow indoors (60–70° F) (germ. 10–20 days); semi-ripewood stem cuttings (as with tender Hedera varieties, at any season; bottom heat helpful)
FELICIA: seed—outdoors after last frost, or moist-cold (30 days) followed by sow indoors (60–70° F) 6–8 weeks before last frost date (germ. 30 days)
FESTUCA: seed—light, sow in situ; cultivars—division
FICUS: seed—light, sow indoors (70–75° F) (germ. 15–20 days); softwood, greenwood, leaf-bud, semi-ripewood cuttings (hardwood for hardy types—take in midwinter and refrigerate, or try later and treat as semi-ripewood cutting); air layering
FILIPENDULA: fresh seed—outdoors, or purchased seed moist-warm (30–42 days) followed by moist-cold (30–42 days) followed by sow indoors (55–60° F) 8–10 weeks before last frost date (germ. 30–90 days); division; root cuttings
FORSYTHIA: seed—(most kinds grown are cultivars; however, sowing could yield new selections and is easy) outdoors, or moist-cold (30 days minimum) and sow indoors (55° F) (germ. 30–90 days); softwood, greenwood, semi-ripewood, hardwood cuttings; layering, tip layering; division of suckers
FOTHERGILLA: softwood, semi-ripewood cuttings (hormone) (note: do not remove from medium once rooted—set in pots of medium or devote a flat to these and allow cuttings to go through winter dormancy before repotting); layering
FRAGARIA: seed—(collect fruits of alpine types and allow them to dry completely, hold dried fruits over a bowl, and rub between fingers—seeds will fall off) outdoors in autumn or spring, or sow indoors (55° F) (germ. 30 days); division of offsets (alpine varieties) or runners (garden strawberries)—peg to medium, soil, or in daughter pots
FRANKLINIA: fresh seed—keep moist, sow outdoors, or sow indoors (60° F) (germ. 14 days with fresh seed) or moist-cold (30 [to 90] days), sow indoors (50–60° F) (germ. up to 3 years); greenwood, semi-ripewood cuttings (hormone) (note: cuttings root readily but dislike transplanting; consider Oasis or rock wool cubes)
FREESIA: seed—outdoors in frost-free climate, or soak in warm water (24 hours), sow indoors (65–75° F) (germ. 25–30 days); division of offsets in autumn
FREMONTODENDRON: fresh seed—outdoors in indigenous climates; semi-ripe, hardwood cuttings
FRITILLARIA: seed—outdoors, germination may take 1–2 years; division of bulblets from mature plants; scaling and chipping, scooping and scoring
FUCHSIA: seed—light, sow indoors (70–75° F) (fresh seed, germ. 21 days; dry seed, 21–90 days); softwood (very small cuttings may be taken; try Oasis cubes), semi-hardwood (mist helpful), hardwood cuttings (best with hardy kinds)
GAILLARDIA: seed—light, sow indoors (70–75° F) (annuals: 4–6 weeks before last frost date, perennials: 6–8 weeks before last frost date) (germ. 21 days); perennial kinds by division; root cuttings
GALANTHUS: seed—outdoors (germ. erratic); division of clumps; chipping or twin scaling
GALIUM: division in spring or autumn
GALTONIA: seed—sow indoors (70° F) 6–8 weeks before last frost date (germ. 15–20 days); offsets, but few are produced
GARDENIA: fresh seed—sow indoors (70–75° F) (germ. 25–30 days); greenwood, semi-ripewood cuttings (hormone and mist helpful) (note: do not remove cuttings from medium once rooted—best to root in single cells in flats)
GAULTHERIA: fresh seed—(collect from fruits in autumn through winter) moist-cold (30 days) followed by light, sow indoors (55– 65° F) (germ. erratic); semi-ripewood cuttings; division of rooted (naturally layered) horizontal stems
GAURA: seeds—sow indoors (70–75° F) 4–6 weeks before last frost date (germ. 14–30 days); semi-ripe stem cuttings in summer with heel; division (dig deep so as not to damage thick root); basal cuttings in spring
GILLENIA: see Porteranthus
GELSEMIUM: seed—outdoors where hardy; semi-ripewood (with hormone under mist), hardwood cuttings
GENISTA: seed—(acid scarification in trade) file (sandpaper) and soak in hot water (12 hours) and then cool to sow indoors (65–70° F) (germ. 14–21 days); softwood, greenwood with some varieties, semi-ripewood stem for most with hormone, hardwood cuttings in climates with mild winters
GENTIANA: seed—moist-cold (2 months) followed by dark, sow indoors (70–75° F) (germ. 14–180 days depending on species); stem-tip cuttings taken from spring bloomers; division after flowering; basal cuttings in autumn from autumn-flowering kinds
GERANIUM: fresh seed—(varies by species) tender: sow indoors (70–75° F) (germ. 3–21 days), hardy: sow indoors (50° F) (germ. 3–90 days) or outdoors in late autumn; division in spring or autumn of hardy varieties; basal cuttings when spring growth slows; root cuttings of some, including alpine species
GERBERA: fresh seed—light, sow indoors (70–75° F) 10–12 weeks before last frost date (germ. 7–14 days); semi-ripe cuttings in summer; division in summer or autumn
GEUM: seed—outdoors in spring or summer, or sow indoors warm (65–85° F [10° F drop at night beneficial]) 8–10 weeks before last frost date (germ. 21–28 days); division in spring, but autumn preferable
GINKGO: fresh seed—light, outdoors, or moist-warm (30–60 days) followed by moist-cold (30–60 days) then light, sow indoors (70–75° F) (germ. 30–60 days); semi-ripewood cuttings root well—even from mature trees (hormone and mist); grafting
GLADIOLUS: seed—sow indoors (70–75° F) (germ. 20–40 days, keep in pots: cormels form first year below grassy foliage); division of cormels, corm; corm cutting producing sections with at least one eye
GLAUCIDIUM: fresh seed—outdoors (note: may take 2 years or longer to germinate; leave initial seedlings in pot until third year to allow for stragglers; seeds treated with gibberellic acid-3 sprout quickly), or sow indoors (50–55° F) (germ. 30–90 days or up to 2 years); division in late winter, early spring of peony-like woody rootstock with dormant buds
GLAUCIUM: seed—sow in situ in spring
GLEDITSIA: seed—hot-water soak (170° F) followed by sow indoors (70–75° F) (germ. 7–14 days) (moist-cold [60–90 days] recommended but not necessary in test with fresh seed); grafting
GLORIOSA: seed—sow indoors (70–75° F) (germ. 30 days); division of tubers
GLOXINIA: seeds—light, sow indoors (70–75° F) (germ. 15–21 days); stem cuttings (bottom heat)
GOODYERA: nodal stem cuttings (allow to callus 48 hours); division in spring
GREVILLEA: seed—soak 48 hours (or moist-cold 30 days), light, sow indoors (70–75° F) (germ. 20–25 days)
GUNNERA: seed—sow indoors (60–70° F) 6–8 weeks before last frost date (germ. 14–60 days); leaf cuttings in spring; division in spring
GYMNOCLADUS: seed—(extremely hard seed coat, sulfuric acid soaks for up to 2 days) try file, hot water, and then 24-hour soak; greenwood, hardwood cuttings
GYPSOPHILA: seed—sow indoors (60–70° F) (sow annual types in situ in spring after all danger of frost is past) (germ. 10 days); basal cuttings; division of perennial types can be done, but all resent root disturbance and for that reason grafting is used for G. paniculata
HABENARIA: division of young tubers with pointed shoots in spring
HAEMANTHUS: seed—sow indoors (60– 65° F) (germ. 7–42 days); offsets
HAKONECHLOA: division
HALESIA: seed—outdoors (may not germinate until second spring), or moist-warm (6–9 months) followed by moist-cold (6–9 months); softwood, semi-ripewood, hardwood stem cuttings (all with hormone)
HAMAMELIS: (varieties propagated vegetatively, but seed is difficult in any event—best [light] outdoors [germ. in second spring]); softwood stem cuttings (early hormone and gentle bottom heat), semi-ripewood possible with hormone and mist, but rooted cuttings must overwinter without disturbance; layering; grafting for hybrids to H. virginiana understock
HAWORTHIA: seed—light, sow indoors (60–65° F) (germ. 21–60 days); offsets
HEBE: softwood, semi-ripewood cuttings (cuttings small, like those of Calluna and Erica—hormone and mist helpful, but mildew may attack cuttings)
HEDERA: softwood, semi-ripewood, hardwood cuttings; layering (note adventitious roots); grafting
HEDYCHIUM: seed—sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 20–25 days); section of rhizome while still dormant in early spring
HELENIUM: seed—outdoors in situ in early spring or early autumn, or sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 7–10 days); division in spring
HELIANTHEMUM: seed—outdoors in situ in spring to summer, or sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 14–21 days); semi-ripe cuttings
HELIANTHUS: seed—outdoors in situ after all danger of frost is past, or sow indoors (75–85° F) 2–3 weeks before last frost date (germ. 5–14 days); perennials only—division in spring or autumn
HELICHRYSUM: seed—light, sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 7–10 days); semi-ripe cuttings in summer for flowering kinds; foliage types—stem-tip cuttings from mid- to late summer (keep foliage dry); division in spring where plants winter-over
HELICTOTRICHON: division in spring or autumn
HELIOPSIS: seed—(species) outdoors in spring to summer, or sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 10–15 days); cultivars: cuttings; cultivars: division
HELIOTROPIUM: seed—sow indoors (70–75° F) 10–12 weeks before last frost date (germ. 14–42 days); greenwood, semi-ripewood cuttings (benefit from bottom heat); root cuttings in autumn with bottom heat
HELLEBORUS: fresh seed—outdoors (many species and hybrids may need two winters before germination), or try moist-warm (56–70 days) followed by moist-cold (56–70 days) sow indoors (60–65° F) (germ. 30–545 days), sowing very fresh seed may bypass long conditioning period; division in spring—carefully pry plantlets apart at crown
HEMEROCALLIS: seed—(species or to create hybrids) outdoors, or moist-cold (42 days) followed by sow indoors (60–70° F) 6–8 weeks before last frost date (germ. 15–60 days); sections of fresh flower scapes may sometimes root at leaf-sheath nodes; division (of established hybrid plants)
HEPATICA: seed—light, outdoors, or moist-cold (30 days) followed by light, sow indoors (50–55° F) (germ. 30–365 days, erratic)
HEUCHERA: seed—(species) light, sow indoors cool (55–70° F) 8–10 weeks before last frost date (germ. 10–60 days); leaf-petiole cuttings; division in spring or autumn
X HEUCHERELLA: division in spring
HIBISCUS: seed—hardy woody species: outdoors, herbaceous kinds: nick and soak 12 hours and then sow indoors (70–75° F) (annuals: 6–8 weeks before last frost date) (germ. 15–30 days, may take longer); herbaceous cuttings in late spring to midsummer; tender woody evergreens: semi-ripewood cuttings, layering; hardy H. syriacus very easy from hardwood, but may be rooted as softwood, greenwood, and semi-ripewood cuttings; grafting
HIPPEASTRUM: fresh seed—sow indoors (70–75° F) (germ. 30–45 days, older seeds take longer); division; chipping
HOSTA: seed—seed can be sown indoors as soon as ripe (sow fresh indoors (50–70° F) (germ. 15–90 days), or dried for spring sowing indoors 6–8 weeks before last frost date; division (note: hostas can be encouraged to produce multiple eyes or buds at crown level by “topping”: in spring, clear away soil at the base of a new shoot to expose the eye at its base from which it sprang; clean the area with a damp paper towel, and make a cut with a snap-blade knife or similar tool through the bud and about ½ inch into the crown; dust with hormone and insert a toothpick into the wound; by autumn, many buds will have formed and the following spring several more shoots than would normally have been produced will appear); root cuttings
HOYA: semi-ripewood cuttings; layering
HUMULUS: seed—herbaceous perennial species: sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 30–90 days, can be erratic), annual types: in situ after all danger of frost is past and soil is warm; leaf-bud cuttings; layering (simple and serpentine) easy in late spring
HYACINTHOIDES: fresh seed—sow outdoors in situ, in flats or drills in nursery bed; division of deep-rooted bulbs (invasive in England, rarely in U.S.)
HYACINTHUS: (difficult from seed, and varieties must be vegetatively propagated); leaf cuttings; division; twin scaling; chipping; scooping; scoring
HYDRANGEA: fresh seed—sow indoors (50° F) (high humidity) (germ. varies depending on species—as short as a few weeks for fresh H. quercifolia); softwood, semi-ripewood (as small as split stem leaf-bud cuttings [see here]), hardwood cuttings; serpentine layering of climbing hydrangea; division of suckers of H. macro-phylla
HYPERICUM: seed—outdoors, or sow indoors (50–55° F) 8–10 weeks before last frost date (germ. 30–90 days, may take longer); softwood, semi-ripewood, hardwood cuttings; division
HYPOESTES: seed—sow indoors (70–75° F) (germ. 10–12 days); herbaceous stem cuttings in spring, semi-ripe cuttings in summer; ground-cover types can be layered
IBERIS: seed—sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 10–15 days), sow in situ after all danger of frost is past (sow indoors annual kinds consecutively for continuous bloom every 10 days from last frost date until mid-July); division of perennial kinds after flowering
ILEX: seed—clean, outdoors, or moistwarm followed by moist-cold and then sow outdoors or indoors (germ. very slow—may take years); softwood, semi-ripewood, hardwood cuttings with hormones (and patience); layering; grafting
ILLICIUM: seed—(dry-stored seed) sow indoors (70–75° F) or in situ when soil warm (germ. 14–30 days, varies); semi-ripewood cuttings; root cuttings
IMPATIENS: seed—light, sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 7–30 days, can be erratic); herbaceous cuttings
INCARVILLEA: seed—outdoors, or sow indoors cool (55–65° F) 8–10 weeks before last frost date (germ. 25–30 days); root cuttings
INDIGOFERA: seed—hot-water soak 24 hours, sow indoors cool (50° F) (30–90 days); semi-ripewood, hardwood cuttings
INULA: seed—outdoors in situ while soil cool, sow indoors (55–65° F) 6–8 weeks before last frost date (germ. 14–42 days); division in spring (in autumn in mild climates)
IPOMOEA: seed—nick seeds and/or 24-hour warm-water soak and then sow in situ, or sow indoors in paper pots or cells (70–75° F) 3–4 weeks before last frost date (germ. 7–10 days)
IRIS: seed—(variable by species) outdoors in spring (except autumn-sow indoors for bulbous types), or moist-cold (90 days) followed by sow indoors (50–65° F) (germ. 30–365 days); division rhizomatous kinds when semidormant in mid- to late summer, Siberian and similar types with offsets in early spring or in midsummer), divide bulbous types (e.g., I. reticulata) when leaves disappear in autumn—these may also be chipped in late summer
ITEA: seed—light, outdoors; evergreen types from semi-ripewood, deciduous kinds from softwood and greenwood cuttings
JACARANDA: seed—file, hot water and then 24-hour soak followed by sow indoors (70–75° F) (germ. 10–15 days); greenwood cuttings
JASMINUM: seed—(some species) sow indoors (70–75° F) (germ. 20–25 days); softwood, semi-ripewood cuttings (hormone), hardwood cuttings in frost-free regions; layering
JUGLANS: seed—light, outdoors in autumn, or moist-cold (90 days) followed by light, sow indoors (50° F) (germ. 30–180 days); edible cultivars grafted to saplings
JUNCUS: ripe seed—outdoors on constantly moist medium; division in early spring
JUNIPERUS: seed—light, outdoors (germ. 2–5 years); evergreen hardwood cuttings in winter are treated as semi-ripewood—wounding and hormone, under mist or with high humidity with bottom heat
JUSTICIA: seed—sow indoors (70–75° F) (germ. 20–25 days); semi-ripewood cuttings
KALANCHOE: seed—light, sow indoors (70–75° F) (germ. 10 days); leaf, semi-ripewood stem cuttings; removal of adventitious leaf growths
KALIMERIS: division in early to mid-spring
KALMIA: seed—light, outdoors, or moist-cold (90 days) followed by light, sow indoors (70–75° F) (germ. 30 days or longer); green-wood and semi-ripewood cuttings (wound); layering in spring
KERRIA: softwood, greenwood, semi-ripewood, hardwood cuttings; divisions of suckers
KIRENGESHOMA: seed—sow indoors (55–65° F) (germ. 30–365 days); division
KNAUTIA: seed—best in situ; basal stem cuttings; division in spring
KNIPHOFIA: seed—light, outdoors in spring to summer, or light, sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 10–20 days); division (transplant large sections, pot small pieces for cold frame)
KOELREUTERIA: seed—nick and soak 48 hours followed by light, sow outdoors, or moist-cold (90 days) followed by light, sow indoors (50–60° F) (germ. 30–60 days or longer); root cuttings
KOLKWITZIA: seed—light, outdoors, high humidity; stem cuttings easy—softwood, greenwood, semi-ripewood, hardwood
LABURNUM: seed—24-hour hot-water soak followed by sow indoors (55–70° F) (germ. 30–60 days); hardwood cuttings; most kinds are varieties propagated by grafting
LACHENALIA: fresh seed—sow indoors (spring) (55–65° F) (germ. 30–120 days); division: scooping; bulbils in late summer
LAGERSTROEMIA: seed—light, sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 15–20 days), or light, outdoors after danger of frost is past; hardwood cuttings
LAMIUM: seed—outdoors in situ, or sow indoors (65–70° F) 8–10 weeks before last frost date (germ. 30–60 days); herbaceous cuttings; division
LANTANA: seed—soak in warm water 24 hours, sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 45–65 days, erratic); greenwood, semi-ripewood cuttings
LARIX: fresh seed—light, outdoors, or light, sow indoors with gentle bottom heat (65–70° F) (germ. 30–90 days), older seed may require moist-cold (60 days); grafting
LATHYRUS: seed—nick and soak in cold water followed by dark, sow indoors cool (55–65° F) 6–8 weeks before last frost date (germ. 10–30 days); perennial species can be divided in spring
LAURUS: seed—(as per Ilex); semi-ripewood cuttings; layering
LAVANDULA: seed—sow indoors (55– 65° F) 6–8 weeks before last frost date (germ. 21–90 days, erratic); softwood, semi-ripewood, hardwood cuttings; layering (mounding) in spring
LAVATERA: seed—sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 15–20 days); softwood, greenwood cuttings
LESPEDEZA: seed—nick or soak followed by sow indoors (70–75° F) (germ. 10–14 days); softwood, greenwood cuttings
LEUCOJUM: seed—fresh when ripe outdoors, or stored in sand in the refrigerator until sowing indoors (55–65° F) (germ. may be erratic); division when variety is dormant
LEUCOTHOE: seed—outdoors, light, acidic medium (peat), or light, sow indoors (60–70° F) (germ. 14–49 days, erratic), seedlings must be left undisturbed for a year or more; greenwood and semi-ripewood stem cuttings
LEWISIA: seed—light, outdoors (germ. 1 or more years); division of basal suckers
LEYCESTERIA: seed—outdoors in autumn where hardy; hardwood cuttings
LIATRIS: seed—sow indoors (55–75° F [temperature reduction at night beneficial]) 6–8 weeks before last frost date (germ. 20–30 days); basal stem cuttings; division in spring
LIGULARIA: seed—sow indoors (55– 65° F) 6–8 weeks before last frost date (germ. 14–40 days, erratic); basal stem cuttings; division in spring
LIGUSTRUM: fresh seed—clean and outdoors, or dry seed—moist-cold (42 days) before spring sowing outdoors; softwood, semi-ripewood, hardwood cuttings; layering
LILIUM: seed—fresh seed germinates more readily, but lilies may germinate in weeks (epigeal) or up to years (hypogeal) after producing a little bulb in the medium (for example, L. candidum, L. henryi, L. martagon); also depending on species: division of offsets; scales; stem cuttings in trench; a few varieties will even root from leaf cuttings (L. longiflorum), and others produce bulbils on stem (place lily seeds in vermiculite in plastic bag for 4–12 weeks—check for leaf or bulblet formation; pot leaf seedlings and grow in light, pot bulblets in medium and refrigerate for 3–6 months, then bring to light and warmth); some lilies’ stems will produce bulbs if laid horizontally in a trench or medium—lift bulbs and stem, bury with just tip exposed
LINARIA: seed—in situ after danger of frost is past, or sow indoors (55–60° F) (21 days of moist-cold may be helpful) (germ. 10–15 days)
LINDERA: fresh seed—clean of fruit and outdoors, or moist-warm (30 days) followed by moist-cold (90 days) then sow indoors (60° F) (germ. 30–60 days); greenwood cuttings with hormone and mist (difficult)
LINUM: seed—best in situ, spring to summer; herbaceous stem cuttings
LIQUIDAMBAR: seed—light, outdoors, or moist-cold (60 days) followed by light, sow indoors (55–65° F) (germ. 30–45 days); greenwood cuttings; layering; grafting for varieties
LIRIODENDRON: fresh seed—light, outdoors, or moist-cold (60 days) followed by light, sow indoors (55–65° F) (germ. 60–90 days); greenwood cuttings; grafting of varieties
LIRIOPE: seed—24-hour soak followed by sowing outdoors in summer, or sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 30 days); division
LISIANTHUS: seed—light, sow indoors (70–75° F) (germ. 10–21 days); division
LITHOPS: seed—light, sow indoors (70–75° F) (germ. 10–40 days)
LOBELIA: seed—annual types light: sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 15–21 days), perennial species: light, outdoors in autumn for spring germination, or moist-cold (90 days) then light, sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 15–20 days); herbaceous cuttings in summer; division
LOBULARIA: seed—light, in situ early spring, or light, sow indoors (55–75° F) 4–6 weeks before setting out while soil still cool and light frost possible (germ. 10–15 days)
LONICERA: softwood, semi-ripewood, hardwood cuttings; layering
LUDISIA: nodal stem cuttings (allow to callus 48 hours); division in spring
LUNARIA: seed—best in situ in summer, or sow indoors (70° F) 6–8 weeks before last frost date (germ. 10–14 days)
LUPINUS: seed—24-hour warm-water soak, nick, dark outdoors in early spring, or sow indoors (55–70° F) (germ. 14–60 days); woody types: softwood or greenwood basal cuttings
LYCHNIS: seed—moist-cold (14 days) followed by light, sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 21–30 days); herbaceous cuttings; division in spring
LYCORIS: fresh seed—outdoors; division of bulblets after flowering
LYSICHITON: fresh seed—outdoors, or sow indoors cool (55–65° F) 10–12 weeks before last frost date, keep medium saturated in bowl of water (germ. 30–60 days, erratic); division in spring
LYSIMACHIA: seed—outdoors best, or sow indoors (55–65° F) (germ. 30–90 days, erratic); herbaceous cuttings; layering (L. nummularia only); division
MAGNOLIA: fresh seed (species are very variable—in some, embryo matures during storage, in others inhibitors may develop with ripening—experiment with near-ripe and stored fruits)—soak seeds 48 hours in warm water with liquid detergent, then clean of all pulp, light outdoors (germ. in following spring), or moist-cold (120 days) followed by light, sow indoors (50° F) (germ. 120 days or longer); softwood, greenwood, semi-ripewood cuttings (wound); layering, air layering; grafting varieties on seedlings
MAHONIA: fresh seed—clean, light, outdoors or moist-cold (21 days) light, sow indoors (acidic medium) (50° F) (germ. 90–120 days); leaf-bud, semi-ripewood cuttings; division
MAIANTHEMUM: fresh seed outdoors
MALUS: seed—clean fruits, outdoors, or moist-cold (60 days), sow indoors (65–70° F) (germ. 30–60 days); grafting
MALVA: seed—outdoors in spring to summer, or sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 5–10 days)
MANDEVILLA: seed—(70–75° F) (germ. 14–30 days); softwood, greenwood cuttings (bottom heat)
MARRUBIUM: seed—sow indoors (50° F) (germ. erratic); basal stem cuttings in summer
MATTEUCCIA: spores—sow indoors cool (65–70° F); divide offsets around crown in early spring
MECONOPSIS: seed—sow indoors (55– 65° F) 6–8 weeks before last frost date (germ. 14–28 days) (the blue poppies are notoriously difficult to grow, orange or yellow M. cambrica is easier and best from fresh seed); division (very carefully) early spring
MELIANTHUS: seed—sow indoors (70–75° F) (germ. 30–180 days, erratic); basal cuttings in spring; division
MELISSA: seed—light, sow indoors (70° F) 8–10 weeks before last frost date (germ. 14–21 days); stem cuttings; division in early spring (potentially invasive mint-family member)
MERTENSIA: fresh seed—outdoors; carefully divide after flowering
MESEMBRYANTHEMUM: seed—dark, sow indoors (65–75° F) 8–10 weeks before last frost date (germ. 15–20 days); cuttings in spring
METASEQUOIA: fresh seed—sow indoors (50–60° F) (germ. 5–20 days); softwood cuttings (mist, bottom heat), hardwood cuttings (store autumn-collected twigs a minimum of 45 days in refrigerator and then hormone dip and move to mist with bottom heat, or plant outdoors in spring)
MICROBIOTA: evergreen hardwood cuttings
MILIUM: fresh seed—light, sow in situ outdoors; division
MILTONIA: rooting of backbulbs (as per Cymbidium)
MIMULUS: seed—moist-cold (21 days) and then light, sow indoors (70–75° F) 10–12 weeks before last frost date (germ. 7–21 days) (or outdoors in spring, light, 45–55° F); herbaceous: stem-tip cuttings, division; woody: softwood, greenwood, semi-ripewood cuttings
MINA: see Ipomoea
MIRABILIS: seed—light, sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 7–21 days); tuber sections in spring in mild climates
MISCANTHUS: seed—outdoors; division in spring (invasive, discourage seed release in warm climates, do not grow near meadows)
MITCHELLA: seed—in situ in autumn; semi-ripe cuttings; division in spring; sections of runners
MONARDA: seed—in situ in early spring through summer, or sow indoors (50–65° F [temperature reduction at night beneficial]) (germ. 15–20 days); herbaceous cuttings; division in early spring (potentially invasive mint-family member)
MONSTERA: semi-ripewood, stem section horizontally placed on medium or leaf-bud cuttings anytime; layering, air layering
MORUS: seed—clean fruits, light outdoors, or moist-cold (30–90 days), light, sow indoors (65–75° F) (germ. 14–30 days); hardwood cuttings; grafting
MUSA: fresh seed—file, soak in hot water and then cool 24 hours, sow indoors (75° F) (germ. 21–30 days); division of offsets
MUSCARI: fresh seed—outdoors; division; chipping
MYOSOTIS: seed—in situ in early spring to winter, or dark, sow indoors cool (65–70° F) 8–10 weeks before last frost date (germ. 14–30 days) (potentially invasive from seed)
MYRICA: seed propagation difficult—wax must be removed from seeds—outdoors in autumn; greenwood cuttings with bottom heat; layering; division of suckers; root cuttings
MYRRHIS: seed—sow in situ, or sow indoors (55–65° F) (germ. 14–40 days)
MYRTUS: seed—soak 48 hours, sow indoors (55–65° F) (germ. 30–90 days, erratic); softwood, semi-ripewood cuttings
NANDINA: fresh seed—clean seed from fruit in autumn and sow indoors cool (65–70° F) (irregular germ. times due to embryo development and storage); greenwood, semi-ripewood cuttings (hormone for both); division of basal offsets
NARCISSUS: fresh seed—outdoors as available (varieties can only be propagated vegetatively, of course, and many hybrid daffodil fruits are barren); division of offsets; twin scaling, chipping
NECTAROSCORDUM: fresh seed—outdoors in protected spot; division of offsets when dormant
NELUMBO: seed—file side of seeds, and then soak in 100° F water 48 hours, remove seed coat and place seed in a bowl of warm water (75–85° F) with another bowl keeping seeds submerged, change water once or twice a day until seeds germinate (germ. 14–30 days), then plant in pot of heavy soil standing in a bowl of water; sections of rhizome in spring (bottom heat helpful); division
NEMESIA: seed—sow indoors (55–70° F) 8–10 weeks before last frost date (germ. 7–21 days)
NEMOPHILA: seed—dark, in situ after danger of frost, or dark, sow indoors (55° F) 6–8 weeks before last frost (germ. 7–21 days)
NEPENTHES: fresh seed—sow on moist sphagnum with high humidity (75–85° F) (germ. 30–90 days); semi-ripe cuttings; air layering
NEPETA: seed—outdoors in situ when soil warm, or sow indoors (60–70° F) 8–10 weeks before last frost date (germ. 7–14 days); herbaceous cuttings in spring; division in spring
NEPHROLEPIS: spores—warm (germ. erratic); division; runners (roll up and pin stringy stolons to daughter pot)
NERINE: seed—sow as soon as harvested in autumn (germ. immediate); division of bulbs in spring before dormant; chipping in summer
NERIUM: seed—light, outdoors in spring, or light, sow indoors (70–75° F) (germ. 30–90 days); greenwood, semi-ripewood cuttings (late summer or any time proper material is available, bottom heat helpful); layering
NICOTIANA: seed—light, sow indoors (70–75° F) (germ. 10–20 days); root cuttings
NIEREMBERGIA: seed—outdoors in situ in early spring or early autumn, or sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 15–30 days)
NIGELLA: seed—in situ or sow indoors repeatedly for continuous blooming (65–70° F) beginning 6–8 weeks before last frost date (germ. 10–15 days)
NUPHAR: division in spring
NYMPHAEA: fresh seed—hardy kinds: sow indoors (55–65° F), tropical varieties: sow indoors (70–75° F)—keep medium saturated in bowl of water (germ. 30–60 days, erratic); leaf cuttings; offsets in spring; root cuttings; division in spring
NYSSA: seed—light, outdoors or moist-cold (90 days) followed by light, sow indoors (50–60° F) (germ. 90–365 days); softwood cuttings sometimes possible; layering; grafting
OCIMUM: seed—light, sow indoors (60–70° F) 4–6 weeks before last frost date (germ. 7–42 days); stem cuttings
OENOTHERA: seed—light, sow indoors (65–70° F [temperature reduction at night beneficial]) 8–10 weeks before last frost date (germ. 15–30 days); stem cuttings; division in spring
OLEA: seed—clean raw seed, crack coat, sow indoors (70–75° F) (germ. 30–120 days); semi-ripewood cuttings
OMPHALODES: seed—sow indoors (65–70° F) 10–12 weeks before last frost date (germ. 14–42 days); division in spring
ONCIDIUM: seed—(very difficult) light, sow indoors (65–75° F) (germ. 90–365 days); division of offset pseudobulbs after flowering; rooting of backbulbs (as per Cymbidium)
ONOCLEA: spores—sow indoors in winter (55–65° F) (germ. 90+ days, erratic); division of rhizomes
ONOPORDUM: seed—sow indoors (55– 60° F) (germ. 30–60 days)
ONOSMA: seed—sow indoors (50° F) 10–12 weeks before last frost date (germ. 30–60 days); semi-ripe cuttings in summer
OPHIOPOGON: seed—soak 24 hours in warm water, sow indoors (65–70° F) 6–8 weeks before last frost date (germ. 30–42 days); division in early spring
OPUNTIA: fresh seed—clean seed from fruit, dark, sow indoors (70° F) (germ. 21 days—varies by species); stem pad cuttings (allow to callus)
ORIGANUM: seed—outdoors after frost, or sow indoors (55–65° F) 6–8 weeks before last frost date (germ. 10 days); cuttings in spring; division in spring
ORNITHOGALUM: seed—hardy species: outdoors in autumn, or moist-cold (21 days) and then sow indoors (55–60° F) (germ. 30–180 days); division of bulblets in autumn
ORONTIUM: fresh seed—sow indoors cool (55–65° F), keep medium saturated in bowl of water (germ. 30–60 days, erratic); division in late spring
OSMANTHUS: seed—sow indoors in pots in autumn and place in cool frost-free place; semi-ripewood nodal tip cuttings or with heel if possible (bottom heat, Oasis or rock wool blocks may work well)
OSMUNDA: ripe spores—outdoors in late spring in covered saucers in bright light, or indoors (see here); division
OSTEOSPERMUM: seed—light, sow indoors (60–65° F) (germ. 10–15 days); softwood, greenwood, semi-ripewood cuttings whenever available
OXALIS: seed—sow indoors (55–70° F) (germ. 14–60 days); tuber sections in spring (hardy) or after flowering (some species are potentially invasive)
OXYDENDRUM: fresh seed—light, sow indoors (60–70° F) under mist; tissue culture
OXYPETALUM: seed—sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 30–90 days); cuttings in spring
PACHYPODIUM: seed—light, sow indoors (70–75° F) (germ. 30–180 days)
PACHYSANDRA: division of stolons (horizontal stems) in spring
PACHYSTACHYS: softwood, greenwood nodal cuttings in summer
PAEONIA: fresh seed—light, outdoors, or moist-warm (90 days) followed by moist-cold (90 days) followed by light, sow indoors (60–70° F) (germ. 270+ days) (two-step germination, see here); division of thick rootstock in autumn; grafting for tree peonies, which are shrubs
PANICUM: seed—outdoors; division of perennial kinds in spring
PAPAVER: seed—sow in situ when seeds available or winter (germ. 10–30 days once temperatures are above 55° F); root cuttings of hardy herbaceous perennial varieties
PARDANCANDA: seed—moist-cold (7 days) prior to sow indoors (70–85° F) 8–10 weeks before last frost date (germ. 14 days); division in spring
PARROTIA: fresh seed—outdoors in autumn, or soak 48 hours, moist-cold (70 days), and sow indoors (germ. erratic); layering in early summer or midautumn; grafting
PARTHENOCISSUS: seed—soak 24 hours followed by moist-cold (42 days) and then light, sow indoors (60–70° F) 8 weeks before last frost date (germ. 60–180 days); softwood, semi-ripewood, hardwood cuttings; layering (simple and serpentine)
PASSIFLORA: seed—(if harvested: let ripe fruit sit for 14 days, then smash and leave for 2 more days, wash seeds in sieve under running water, dry) soak seeds for 24 hours in hot water and then sow indoors (70–75° F) (germ. 30 days, but older seed may take up to 365 days); softwood, semi-ripewood cuttings; layering
PAULOWNIA: seed—nick, soak 48 hours in hot and then warm water (may be pre-germinated on moist paper towel in plastic bag in sunlight), light, sow indoors (55–70° F) (germ. 30–60 days); root cuttings
PELARGONIUM: seed—sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 3–21 days); greenwood, semi-ripe stem cuttings, expose cut 24 hours to promote callus (see here); some kinds have tubers that can be removed and potted
PENNISETUM: seed—sow indoors (70° F) 6 to 8 weeks before last frost date (germ. 15–21 days); division in spring
PENSTEMON: seed—light, outdoors, or light, sow indoors (55–60° F) 8–10 weeks before last frost date (germ. 18–21 days); stem cuttings in spring or autumn for cold frame; division of basal offsets and basal cuttings of some
PEPEROMIA: seed—sow indoors (70–75° F) (germ. 15–30 days); stem-tip, leaf-petiole cuttings; division
PEROVSKIA: softwood cuttings in spring (subshrub)
PERSEA: seed—soak cleaned seed in hot water (120° F) for half an hour, sow indoors (70–75° F); grafting to disease-resistant understock
PETASITES: seed—light, sow indoors (55–60° F) (germ. 30–90 days); division in spring
PHACELIA: seed—dark, sow indoors (55– 60° F) (germ. 12–30 days)
PHALAENOPSIS: remove rooted offsets or promote keikis—in near-sterile environment, cut away bracts covering dormant buds along underside of flower spikes with sterile blade or scalpel, then smear special hormone and vitamin paste over bud; small plantlets or keikis will be produced soon after that can be pegged to medium to produce roots
PHILADELPHUS: seed—outdoors, or moist-cold helpful (42–56 days), sow indoors (65–70° F) (germ. 30–60 days); stem cuttings easy—softwood, greenwood, semi-ripewood, hardwood
PHILODENDRON: seed—sow indoors (70–75° F) (germ. 30–120 days); leaf-bud, softwood, semi-ripewood stem cuttings; layering (easy—simple, serpentine, air layer-ing—note aerial roots)
PHLOMIS: seed—sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 30–90 days); herbaceous: division in spring; woody: semi-ripe (keep leaves dry, may be rooted in cold frame), hardwood cuttings
PHLOX: seed—annual varieties—dark, sow indoors (55–65° F) 6–8 weeks before last frost date (germ. 10–21 days), summer-flowering perennials: dark, outdoors in autumn, or moist-cold (30 days) followed by sow indoors (70–75° F) (germ. 25–30 days); perennials: stem cuttings in early spring; division in spring (autumn in mild climates); summer-blooming perennials from root cuttings
PHORMIUM: seed—sow indoors (60– 65° F) 10–12 weeks before last frost date (germ. 30–180 days); division in spring
PHOTINIA: most types from greenwood or semi-ripewood cuttings (do well with hormone treatment and in rock wool or Oasis cubes [plugs])
PHUOPSIS: seed—light, outdoors in autumn best, or light, sow indoors (50– 65° F) (germ. 30–40 days); stem cuttings or sections of runners in summer; division in spring before flowering (may be invasive if happy)
PHYGELIUS: seed—outdoors in spring or summer, or sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 10–14 days); softwood basal cuttings in spring, semi-ripe cuttings in late summer; division in spring (in autumn in mild climates)
PHYSALIS: seed—light, sow indoors (70–75° F) (germ. 10–30 days); division in early spring
PHYSOCARPUS: softwood, greenwood, semi-ripewood cuttings
PHYSOSTEGIA: seed—sow indoors (60– 65° F [temperature reduction at night beneficial]) 8–10 weeks before last frost date (germ. 30–180 days); division in spring (potentially invasive mint-family member)
PICEA: seed—moist-cold (21 days) followed by light, sow indoors (55° F) (germ. 30–60 days); semi-ripe cuttings; evergreen hardwood cuttings require bottom heat
PIERIS: seed—light, sow indoors (65–70° F) (germ. 30–70 days); greenwood, semi-ripewood cuttings; layering
PILEA: seed—light, sow indoors (50–65° F) (germ. 30–40 days)
PINUS: seed—soak 24 hours and then moist-cold (42 days) followed by light, sow indoors (55–65 ° F) (germ. 30–60° F); grafting
PITTOSPORUM: seed—pour boiling water over seed in sieve and then light, sow indoors (55° F) (germ. 30–60 days); semi-ripewood cuttings; layering; grafting
PLATANUS: fresh seed—outdoors; hardwood cuttings
PLATYCODON: seed—light, sow indoors (70° F) 6–8 weeks before last frost date (germ. 15–30 days); semi-ripe cuttings in summer; division in spring
PLECTRANTHUS: seed—light, sow indoors (70–75° F) 8–12 weeks before last frost date (germ. 1–15 days); stem cuttings (bottom heat helpful) anytime, but fastest in late winter to early summer
PLUMBAGO: seed—sow indoors (70° F) (germ. 25–30 days); softwood, greenwood, semi-ripewood cuttings
PLUMERIA: seed—24-hour soak, sow indoors (65–75° F) (germ. 30–180–30 days); hardwood cuttings, dry ends in cool dark place and then insert in medium at 70° F
PODOCARPUS: seed—outdoors in climates where plants are hardy; semi-ripewood cuttings
PODOPHYLLUM: fresh seed—light, outdoors best, or moist-cold (30 days) followed by light, sow indoors (65–70° F) (germ. 35–180 days); division of rhizomes after blooming
POLEMONIUM: seed—sow indoors (70–75° F [reduce temperature at night]) 8–10 weeks before last frost date (germ. 20–25 days); division in spring
POLYGALA: seed—hardy types: light, outdoors in autumn, less hardy and tender species: light, sow indoors (70° F) (germ. 25–30 days); softwood, greenwood, semi-ripewood nodal cuttings
POLYGONATUM: seed—outdoors in autumn, or moist-cold (30 days) and then sow indoors or cold frame (50° F) (germ. 30–545 days); division spring (in autumn in mild climates)
POLYPODIUM: spores—sow indoors (65–70° F); divide sections of rhizome with leaves in early spring
POLYSTICHUM: spores—sow indoors (65–70° F); divide offsets around crown in early spring; root “bulbils” (adventitious plantlets) while still attached to midrib of frond, pin to medium
PONCIRUS: seed—moist-cold (30–90 days), sow indoors (65–70° F) (germ. 30 days); semi-ripewood cuttings (hormone, mist, and bottom heat)
PONTEDERIA: fresh seed—sow indoors cool (55–65° F), keep medium saturated in bowl of water (germ. 30–60 days, erratic); division in late spring
POPULUS: ripe seed—lay seed and fluff on medium in pots, cover with grit, and set in cold frame (at 50° F, germ. rapid); hardwood cuttings in late autumn to late winter; grafting; division of suckers in late winter
PORTERANTHUS (GILLENIA): seed—outdoors; division in spring or autumn
POTENTILLA: seed—herbaceous perennials: outdoors in autumn or early spring, or sow indoors (65–70° F) 8–10 weeks before last frost date (germ. 14–30 days); woody: greenwood, semi-ripewood, hardwood cuttings; division
PRIMULA: varies by species, in general for hardy perennials: seed—light, sow outdoors in appropriate climates, from autumn to late winter, or moist-cold (30 days) and then light, sow indoors (60–65° F) 8–10 weeks before last frost date (germ. 21–40 days); division after flowering for early-spring blooming, in early spring for late-spring flowering, gouging in early spring
PRUNUS: seed—wash of all pulp, then outdoors in protected place, or moist-cold (90 days or longer) followed by sow indoors (65–70° F) (germ. 30–60 days); semi-ripewood, hardwood cuttings; (some shrub types—layering); grafting
PULMONARIA: seed—sow indoors (60– 65° F) 7–9 weeks before last frost date (germ. 30–42 days); division in late winter; root cuttings
PULSATILLA: fresh seed—outdoors best, dry seed—nick, sow indoors (60–70° F) (germ. 30–180 days); tip cuttings; division
PUNICA: seed—soak 24 hours followed by light, sow indoors (70–75° F) (germ. 30–40 days); softwood, greenwood, hardwood cuttings
PYRACANTHA: seed—(squash berries and wash over sieve in running water) moist-cold (42–90 days) followed by light, sow indoors (50° F) (germ. 40–180 days); green-wood, semi-ripewood, hardwood cuttings
PYRUS: seed—clean seed, outdoors, or moist-cold (90 days) (if seeds germinate in refrigerator, surface-sow indoors with fine covering of grit or vermiculite); grafting to seedlings—varieties are vegetatively propagated
QUERCUS: seed—light, outside in protected place, or soak 24 hours followed by moist-cold (90 days minimum, radicle may emerge under refrigeration) and then light, sow indoors (50° F) (germ. 120–365 days); semi-ripe cuttings in rock wool or peat and perlite, bottom heat; grafting
RAMONDA: seed—light, outdoors 2 weeks before last frost date, or light, sow indoors (55–60° F) 6–8 weeks before last frost date (germ. 30–60 days); leaf cuttings; division of offsets in summer
RATIBIDA: seed—sow indoors (70–75° F [reduce temperature at night]) (germ. 21–42 days); division
RHEUM: seed—sow indoors (60–65° F) 8–10 weeks before last frost date (germ. 21–42 days); division of thick rootstock
RHIPSALIS: seed—clean from berries, sow indoors (65–75° F)(germ. 30–90 days); semi-ripe stem cuttings, allow to callus overnight (flat stem, see here)
RHODOCHITON: fresh seed—(soak if dry) sow indoors (65–70° F) 6–8 weeks before last frost date (germ. 14–60 days); stem cuttings in spring to summer
RHODODENDRON: fresh seed—outdoors, light (but shaded from direct sunlight), high humidity, acidic medium (peat-based), or light, sow indoors (50–60° F) (germ. 50–90 days); deciduous: softwood cuttings in early spring with hormone, cool location with high humidity or mist; small-leaved evergreen: nodal greenwood cuttings; large-leaved evergreen: semi-ripewood, leaf-bud or stem cuttings with leaf area reduced by trimming, wound, hormone—bottom heat helpful in outdoor frame (55–60° F), or Nearing frame (see here); layering; grafting
RHUS: seed—nick or soak 24 hours, sow indoors (65–70° F) (germ. 30–90 days); division in late winter; root cuttings in winter
RIBES: softwood, semi-ripewood, hardwood cuttings; layering; grafting
RICINUS: seed—nick, or soak in warm water 24 hours and then sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 14–21 days)
ROBINIA: seed—light, outdoors, or soak in hot water 24 hours followed by light, sow indoors (70–75° F) (germ. 7–30 days); division; root cuttings
RODGERSIA: seed—light, outdoors, or light, sow indoors (55–60° F) 6–8 weeks before last frost date (germ. 14–60 days); division in spring
ROHDEA: seed—species: fresh, clean, sow outdoors; cultivars: division in spring
ROSA: seed—light, outdoors, or moist-cold (90 days) followed by light, sow indoors (55° F) (germ. 30–365 days or longer, erratic)
ROSMARINUS: semi-ripewood, evergreen hardwood cuttings
RUBUS: softwood, semi-ripewood, leaf-bud, hardwood cuttings; layering (simple, serpentine, tip layering, mounding); division
RUDBECKIA: seed—light, sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 5–21 days); stem cuttings in spring; division in spring
RUTA: seed—sow indoors (60–65° F) (germ. 30–42 days); greenwood, semi-ripewood cuttings (note: plant parts can cause skin reaction in sunlight—wear gloves, cut in shade)
SABAL: fresh seed—soak 48 hours in warm water (change once or twice), wash seed, sow on moist paper towel in plastic bag (70° F), pot in medium and fertilize once germinated; division
SAGINA: seed—outdoors in spring while still cool, or sow indoors (55° F) 6–8 weeks before last frost date (germ. 10–25 days); division in spring
SAGITTARIA: fresh seed—sow indoors cool (55–65° F), keep medium saturated in bowl of water (germ. 30–60 days, erratic); division of basal suckers and tubers in spring
SAINTPAULIA: seed—light, sow indoors (70–75° F) (germ. 30–60 days); stem, leaf cuttings, leggy older plants can have stem and top rosette removed and rooted as stem cutting; division of basal rosettes
SALIX: fresh seed—sow indoors (60–65° F) at once, as viability very short (germ. 1–2 days); shrub willows and alpine kinds: root readily from softwood and semi-ripewood cuttings, which appreciate high humidity; tall types: easiest from hardwood cuttings in late winter; grafting
SALVIA: seed—tender and annual varieties: light, sow indoors (70–80° F) 6–8 weeks before last frost date (germ. 7–21 days); hardy perennials: moist-cold (30 days) followed by light, sow indoors (65–70° F) 6–8 weeks before last frost date (germ. 14–30 days); hardy herbaceous perennials: semi-ripe stem cuttings in late summer, division of clump-forming types; tender woody plants: softwood, semi-ripewood nodal cuttings, green to semi-ripe cuttings in late spring to late summer (to carry over indoors under lights or in greenhouse)
SAMBUCUS: fresh seed—clean and outdoors (germ. first or second spring); softwood, semi-ripewood (nodal), hardwood (with heel cuttings); grafting
SANGUINARIA: seed—sow indoors (50– 55° F) 8–10 weeks before last frost date (germ. 30–90 days); division; rhizome sections in early spring or late summer when dormant
SANGUISORBA: seed—outdoors in early spring or autumn, or sow indoors (50–55° F) 10–12 weeks before last frost date (germ. 30–60 days); division in spring
SANSEVIERIA: leaf cuttings are possible, but varieties must be vegetatively reproduced by cutting of “suckers” or new growths via rhizomes
SANTOLINA: seed—moist-cold (30 days) followed by sow indoors (65–70° F) 8–10 weeks before last frost date (germ. 15–30 days); semi-ripewood cuttings
SARCOCOCCA: seed—sow indoors (55– 65° F) (germ. 30–120 days)
SARRACENIA: seed—moist-cold (7 days) followed by light, sow indoors (60–70° F) 8–10 weeks before last frost date (germ. 30–90 days), sow on moist paper towel or whole sphagnum moss kept constantly moist; division in spring or autumn in mild climates
SASSAFRAS: fresh seed—clean seed of flesh, outdoors; root cuttings in winter
SAXIFRAGA: seed—outdoors or in cold frame in autumn, or moist-cold (30 days) and sow indoors (55–60° F) (germ. 14–60 days); division; division of basal offsets in spring to root in medium (S. stolonifera and varieties have runners like those of strawberries, S. granulata has “bulbils” in leaf axils to “sow” as seeds in spring)
SCABIOSA: seed—sow indoors (70–75° F) (germ. 10–15 days), annuals: 4–5 weeks before last frost date, perennials: 8–10 weeks (65–70° F) (germ. 10–15 days); division; basal stem cuttings in midspring
SCHEFFLERA: seed—clean of fleshy pulp, sow indoors (75° F) (germ. 20–30 days); semi-ripewood, leaf-bud cuttings; layering, air layering
SCHIZOPHRAGMA: seed—moist-cold (90 days) followed by sow indoors (60– 65° F) (germ. variable); greenwood (nodal) cuttings; serpentine layering
SCHLUMBERGERA: flat stem cuttings, at least one segment long
SCILLA: seed—outdoors in autumn, or moist-cold (21 days) and then sow indoors (50° F) (germ. 30–180 days); division of offsets in autumn; chipping in late summer
SCROPHULARIA: division of variegated form; basal stem cuttings in spring
SEDUM: seed—hardy types: outdoors in autumn, or moist-cold (30 days) followed by sow indoors (60–65° F) (germ. 14–180 days); semi-ripe cuttings, leaf cuttings of tender kinds (thick stems may need exposure to air for 24 hours to callus before sticking); division in spring
SEMPERVIVUM: seed—sow indoors (70° F) (germ. 14–42 days)—not true from seed; division of offsets
SENECIO: seed—light, sow indoors (65– 75° F) 8 weeks before last frost date (germ. 10–21 days); greenwood, semi-ripewood cuttings; division of perennial types
SENNA: seed—scarification followed by sow indoors (70–80° F) (germ. 7–30 days)
SEQUOIA: seed—(store refrigerated if necessary) light, sow indoors (65–70° F) (germ. 7–60 days, erratic)
SEQUOIADENDRON: seed—(store refrigerated if necessary) light, sow indoors (65–70° F) (germ. 7–60 days, erratic); green-wood tip cuttings
SHORTIA: fresh seed—outdoors, or moist-cold (21 days) followed by sow indoors (60– 65° F) 6–8 weeks before last frost date (germ. 30–60 days); division in early spring
SIDALCEA: seed—sow indoors (50° F) 6–8 weeks before last frost date (germ. 14–42 days); division in autumn
SILENE: seed—sow indoors (70–75° F) 8–10 weeks before last frost date (germ. 15–20 days); perennials: stem cuttings in spring
SILPHIUM: fresh seed—nick, outdoors in autumn; division in spring
SINNINGIA: seed—light, sow indoors (70–75° F) (germ. 10–21 days); leaf cuttings (sections or petiole); sections of tuber in spring; basal cuttings (as for tuberous begonia)
SINOCALYCANTHUS: seed—outdoors in autumn; greenwood, semi-ripewood cuttings; division of suckers
SISYRINCHIUM: seed—outdoors in autumn, or moist-cold (21 days) and then sow indoors (60–65° F) (germ. 30–180 days); division in spring
SKIMMIA: seed—soak 24 hours followed by moist-cold (30 days) and then light, sow indoors (50–60° F) (germ. 30–180 days); greenwood, semi-ripewood cuttings
SMILACINA: seed—light, outdoors best, or moist-cold (30 days) followed by light, sow indoors (60–65° F) (germ. 30–180 days)
SOLANUM: seed—light, sow indoors (70– 80° F) (germ. 14–21 days); softwood, semi-ripewood cuttings (easy to root, but nodal stem cuttings taken of compact growth are less prone to disease)
SOLDANELLA: fresh seed—light, outdoors, or moist-cold (30 days) and then light, sow indoors (55–60° F) (germ. 30–180 days)
SOLENOSTEMON: see Coleus
SOLIDAGO: seed—outdoors in early spring, or sow indoors (50° F) 6–8 weeks before last frost date (germ. 14–42 days); division
SOPHORA: seed—soak in hot water 24 hours followed by light, sow indoors (70–75° F) (germ. 7–30 days); semi-ripewood cuttings of evergreen types; grafting
SORBARIA: seed—outdoors in autumn; softwood, greenwood, semi-ripewood, hardwood cuttings; layering; division
SORBUS: fresh seed—just-ripe seed may be germinated at once, clean seed of pulp, sow outdoors in autumn—otherwise, moist-cold (120 days—check seeds; if any germinate, pot at once) and then light, sow indoors (65–70° F) (germ. 120–180 days); grafting
SPARAXAS: seed—sow indoors (50– 55° F) 8–10 weeks before last frost date (germ. 30–90 days); division of offsets
SPATHIPHYLLUM: division
SPIGELIA: seed—light, outdoors, cold frame, or moist-cold (30 days) followed by light, sow indoors (60–70° F) (germ. 30–60 days); division in late winter
SPIRAEA: seed—sow indoors (55–65° F) (germ. 30–40 days); softwood, semi-ripewood, hardwood cuttings; division
STACHYS: seed—light, sow indoors (70–75° F [reduce temperature at night 10° F]) 8–10 weeks before last frost date (germ. 14–30 days); division; basal cuttings to root
STACHYURUS: seed—outdoors in autumn; greenwood nodal or heel cuttings; layering
STAPELIA: seed—light, sow indoors (65–70° F) (germ. 7–30 days); greenwood, semi-ripewood cuttings—let cut end dry for a day or two to callus before setting in medium (as per succulents)
STAPHYLEA: fresh seed—outdoors, or moist-warm (120 days) followed by moist-cold (90 days) and then sow indoors (65° F) (germ. 30 days); greenwood cuttings with heel
STEPHANANDRA: fresh seed—outdoors, or moist-warm (90 days) followed by, moistcold (90 days) and then sow indoors (65° F) (germ. 21–30 days); nodal or internodal greenwood cuttings; layering
STEPHANOTIS: seed—72-hour soak (wash and change water) followed by sow indoors (75–80° F) (germ. 30–180 days); semi-ripewood cuttings; layering
STEWARTIA: seed—moist-cold (84 days), sow outdoors or indoors as long as temperature remains above 50° F at night (germ. up to 3 years); softwood cuttings
STIPA: seed—outdoors in spring, or sow indoors (70° F) 6–8 weeks before last frost date (germ. 21–30 days); division in spring
STOKESIA: seed—sow indoors (70° F) 8–10 weeks before last frost date (germ. 20–30 days); division in early spring
STRELITZIA: seed—sow indoors (70–75° F) (germ. 14–60 days); division of rooted offsets
STREPTOCARPUS: seed—light, sow indoors (55–65° F) (germ. 15–30 days); stem cuttings of some, leaf cuttings; division
STROBILANTHES: stem-tip cuttings in spring; division in spring; basal cuttings in spring
STYRAX: seed—sow indoors (55–65° F) (germ. 30–90 days or longer); softwood cuttings; layering of shrubby kinds
SYMPHORICARPOS: seed—moist-warm (90 days) followed by moist-cold (90 days) to sow indoors or out in spring (germ. the following spring); softwood, semi-ripewood, hardwood cuttings; division
SYMPHYTUM: division; root cuttings (variegated types will not carry that characteristic through root cuttings)
SYMPLOCARPUS: fresh seed—outdoors, or moist-cold (90 days) followed by moist-warm (90 days) and then sow indoors (55– 65° F—keep medium saturated) (radicle emerges 7–21 days), leaf emerges after second moist-cold and moist-warm treatments
SYNGONIUM: semi-ripe stem cuttings; layering
SYRINGA: seed—(species only—most are cultivars) moist-cold (21 days) followed by light, sow indoors (70° F) (germ. 14–60 days); softwood cuttings taken from new growth as blossoms fade; layering; division of suckers while dormant in late winter; root cuttings in autumn
TANACETUM: seed—sow in situ in spring; division in spring; basal cuttings in spring
TAXODIUM: seed—moist-cold (30 days) and then light, sow indoors (70° F) (germ. 14–60 days); softwood (under mist), hardwood cuttings
TAXUS: seed—clean (wash hands), moist-warm (90 days) followed by moist-cold (90 days) and then moist-warm again (90 days) followed by light, sow indoors (70° F) (germ. 365 days or longer); semi-ripewood cuttings (hormone, wounding perhaps, helps—mist accelerates rooting); grafting
TELLIMA: seed—outdoors, or moist-cold (60 days) followed by sow indoors (55– 60° F) (germ. 30–90 days); division in spring or autumn in mild climates
TEUCRIUM: seed—outdoors, or sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 25–30 days); softwood, greenwood, semi-ripewood (nodal) cuttings; division in spring
THALICTRUM: fresh seed—outdoors best (germ. 15–21 days [erratic, however, up to 735 days]); division in early spring
THERMOPSIS: seed—nick or 24-hour soak followed by sow outdoors in early spring, or indoors (70–75° F) 6–8 weeks before last frost date (germ. 15–30 days); division in spring
THUJA: seed—moist-cold (30 days) followed by light, sow indoors (55° F) (germ. 14–60 days)
THUNBERGIA: seed—sow indoors (70–75° F) 6–8 weeks before last frost date (germ. 14–21 days); greenwood (nodal) cuttings
THYMUS: seed—light, outdoors 2–3 weeks before last frost date, or light, sow indoors (55–65° F) 6–8 weeks before last frost date (germ. 15–30 days); division
TIARELLA: seed—outdoors in autumn, or sow indoors (50° F) (germ. 14–90 days); division in early spring, division of offsets from runners of some
TIBOUCHINA: seed—light, sow indoors (60–70° F) (germ. 30–90 days); greenwood, hardwood cuttings in frost-free areas
TILIA: just-ripe seed—collect before inhibitors develop, outdoors; layering; grafting (budding)
TILLANDSIA: seed—light, sow fluffy seeds over medium and cover with grit indoors (60–70° F) (germ. 30–90 days); division of offsets (pups)
TITHONIA: seed—light, sow indoors (70° F) 6–8 weeks before last frost date (germ. 5–14 days)
TOLMIEA: peg leaves with viviparous growths; division in spring
TRACHELOSPERMUM: greenwood and semi-ripewood cuttings (bottom heat); layering, serpentine layering where hardy outdoors
TRADESCANTIA: seed—light, sow indoors (70–75° F [reduce temperature 10° F at night]) 6–8 weeks before last frost date (germ. 30–40 days); nodal cuttings; division in spring (hardy species may be invasive)
TRICYRTIS: seed—light, sow indoors (65–70° F) 6–8 weeks before last frost date (germ. 30–90 days); division in spring
TRILLIUM: fresh seed—outdoors, or moist-warm (90 days) followed by moist-cold (90 days) followed by sow indoors (50– 60° F) (germ. 365+ days) (see here, sowing “Green”); division of rhizomes after bloom
TROLLIUS: fresh seed—outdoors best in late summer, or with dry seeds moist-cold (30 days) followed by sow indoors (spring) (50° F) (germ. 30–365 days); division after flowering
TSUGA: seed—prior to sowing, expose dry-stored seeds to moist-cold (21 days) and sow in spring, light, outdoors, or light, indoors (60° F) (germ. 7–60 days); semi-ripewood cuttings in autumn (bottom heat)
TULIPA: seed—outdoors best for species, or moist-cold (30–60 days) followed by sow indoors (50° F) (germ. 60–90 days)
TYPHA: division in spring
ULMUS: fresh seed—outdoors; softwood, greenwood cuttings; grafting (budding)
UVULARIA: fresh seed—outdoors best when ripe in late summer; division in spring
VACCINIUM: (blueberry) seed—clean seeds of pulp and then light, outdoors in protected spot, acidic medium (high percentage of peat as per rhododendron) (germ. 365 days or longer); highbush and commercial blueberries: softwood cuttings, evergreen types: semi-ripewood, deciduous types: hardwood cuttings; cranberry: layering; low-bush blueberry: cuttings of rhizome in perlite with bottom heat; division
VALERIANA: seed—outdoors in early spring, or sow indoors (70° F) 10–12 weeks before last frost date (germ. 21–25 days); division in spring or autumn in mild climates; root cuttings
VANCOUVERIA: division
VANDA: sections of stems with or without aerial roots can be removed, wrapped with damp sphagnum, and encouraged to root
VELTHEIMIA: seed—sow indoors (55– 65° F) 8–10 weeks before last frost date (germ. 30–90 days); leaf cuttings; bulblets in spring
VERATRUM: seed—outdoors best, or moist-cold (30 days) followed by sow indoors (55–60° F) (germ. 90–365 days); division in early spring
VERBASCUM: seed—outdoors in spring while still cool, or sow indoors (55–60° F) 6–8 weeks before last frost date (germ. 14–30 days); root cuttings in early spring
VERBENA: seed—dark, sow indoors (65° F) 8–10 weeks before last frost date (germ. 14–90 days); cuttings in spring or semi-ripe in autumn to overwinter in cold frame
VERNONIA: seed—light, outdoors when fresh, or store dry in refrigerator followed by light, late-winter sow indoors (55–60° F) (germ. 21–40 days); division in spring or after flowering in autumn
VERONICA: seed—light, sow indoors (70° F) 8–10 weeks before last frost date (germ. 15–30 days); semi-ripe cuttings in summer; division after flowering
VERONICASTRUM: seed—light, sow indoors (55–60° F) (germ. 21–40 days); semi-ripe cuttings in summer; division after flowering
VIBURNUM: seed—squash ripe fruits, sow indoors together, cover with grit to go outdoors in protected spot, or clean, moist-warm (90 days) followed by moist-cold (90 days) and then moist-warm again (90 days) prior to light, sow indoors (70° F) (germ. 365 days or longer); greenwood, semi-ripewood, hardwood (deciduous) cuttings; layering; grafting
VINCA: seed—dark, sow indoors (70–75° F) (germ. 15–30 days); greenwood, semi-ripewood internodal cuttings; layering; division
VIOLA: seed—most, including pansy types: moist-cold (14 days) followed by dark, sow indoors (65–75° F) 8–10 weeks before last frost date (germ. 14–21 days). V. odorata: outdoors only, in autumn; division in spring. V. tricolor (seed only): best dark, outdoors in autumn or dark, indoors (65–75° F) 10–12 weeks before last frost date (germ. 14 days); stem-tip cuttings; layering (mounding) may work with low-growing species, use well-drained medium
VITEX: seed—outdoors in spring or autumn outdoors in protected spot in mild climates or cold frame; greenwood, semi-ripewood cuttings
VITIS: softwood, semi-ripewood nodal (reduce leaf area), hardwood cuttings (may be as small as to include one node, wound above and below dormant buds) (hormone for all cuttings); layering (serpentine); grafting
WALDSTEINIA: seed—outdoors or cold frame in autumn, or moist-cold (30 days) followed by sow indoors (55–60° F) (germ. 14–60 days); layering (serpentine); offsets via runners
WASHINGTONIA: fresh seed—soak 48 hours in warm water (change once or twice), wash seed, sow on moist paper towel in plastic bag (70° F), pot in medium and fertilize once germinated
WEIGELA: seed—outdoors in spring; most cultivars: softwood, semi-ripewood, hardwood cuttings
WISTERIA: seed—(seed-grown plants are useful for grafting, but rarely as varieties and take years to flower) nick and soak in hot water, sow indoors (55–65° F) 6–8 weeks before last frost date (germ. 30–60 days); softwood (side shoots with close nodes), hardwood cuttings; layering (serpentine); root cuttings taken in late winter will sprout readily if potted and placed over bottom heat
XANTHORHIZA: seed—outdoors in autumn; greenwood cuttings; division in early spring or autumn
YUCCA: seed—outdoors in spring, or soak 24 hours followed by sow indoors (70–75° F) (germ. varies by species, up to 365 days); softwood cuttings; division of suckers, rhizomes and swollen buds on rhizomes (toes) in early spring; root cuttings
ZANTEDESCHIA: seed—light, outdoors in warm climates, or light, sow indoors (70– 80° F) (germ. 30–90 days); sections of tubers with eyes
ZAUSCHNERIA: seed—light, outdoors in spring only where hardy, light, sow indoors (60–65° F) (germ. 30–60 days); stem cuttings in autumn; division in spring
ZEBRINA: nodal stem cuttings; layering, basketing; division
ZELKOVA: seed—moist-cold (14 days) followed by light, sow indoors (50–70° F) (germ. 14–60 days); grafting
ZENOBIA: fresh seed—outdoors, light but shaded from direct sunlight, high humidity, acidic medium (peat-based), or sow indoors (50–60° F) (germ. 50–90 days); semi-ripewood nodal cuttings
SOWING SUMMARY
Most seeds of hardy plants are sown outdoors from autumn to winter, when the garden is quiet and the task can be relaxed—even welcome. But seeds preconditioned indoors* and those of warm-weather annuals and perennials are sown in a flurry of activity beginning in late winter. To avoid becoming overwhelmed, start slowly, perhaps with only three pots and three varieties. Having an area devoted to this activity will make the experience more comfortable. Here is a synopsis of procedures described in Chapter 5, “Sowing.”
Outdoor Sowing of Winter-Hardy Seeds:
1. Harvest fruits when ripe. Clean seeds from dry fruits of extraneous material and wash seed from moist fruits of all pulp following soaking.
2. Assemble clean 3½-inch square pots for each species, or flats for mass sowing.
3. Fill containers with moistened medium, strike off the excess and tamp gently. Add more medium to bring it up to the pot rim and tap on the potting bench to level the mix. (For tiny seeds and those requiring light for germination, see step 5.)
4. Distribute seeds uniformly. Press large ones into the medium to a depth that equals their thickness. Add medium up to the pot rim and tap gently.
5. Cover the surface with a thin layer of grit or very coarse sand. Use fine grit for small seed, coarser for larger ones. The layer should be just thick enough to obscure the medium. Tiny seeds and ones requiring light may be sown on top of the grit layer.
6. Place pots or flats in trays with 1 to 2 inches of water until the grit darkens—about a half hour.
7. Place containers in the screen-covered box outdoors.
Indoor Sowing of Tender Perennials, Annuals, and Preconditioned* Seeds:
1. Determine the sowing date, often included on commercial packets and in the Generic Guide to Propagation. Follow steps 2 through 6, above.
2. Bring pots or flats to your indoor germination location: sunny window, greenhouse bench, or indoor light set-up. If using fluorescent lights, place pots 3 inches below the tubes. Set a timer for 18 hours of light per day. Or provide a window with as much sunlight as possible or a bright area in the greenhouse. Seeds that require darkness for germination must be covered with an opaque card or aluminum foil. Most seeds appreciate gentle heat from below, and the recommended temperature range should be maintained until true leaves appear. (Check seeds in darkness religiously and remove cover once sprouted.)
3. If seeds are allowed to dry once they have absorbed water, they will die. Maintain moisture in the medium. Lift pots to judge weight and become familiar with properly moistened pots.
4. Keep the relative humidity high (above 40 percent). Flats may be draped with loose-fitting plastic film or rigid domes set ajar. Individual pots can be set into open plastic zipper bags or on pebbles kept moist in a tray. The floral cart can be draped in a plastic-film tent. The greenhouse may require a humidifier or misting unit.
5. Once seedlings emerge, the distance from the top of the leaves to the fluorescent tubes must be kept around 3 inches by raising the lights or lowering pots. The medium can be slightly drier and temperatures lower. A 5–10°F drop at night or when the lights are off is helpful.
Packaged Seed of Hardy-Plants from Societies; Mail-Order Sources; or Gathered from the Garden, Cleaned, and Stored Dry:
1. Determine the sowing date.
2. Soak dried seeds that originated in moist fruits in water overnight (change water a few times). Condition if necessary.* Follow steps 2 through 6 for Fresh Seeds, above.
3. Place containers outdoors or indoors as required.