Dahlia

DAHLIA

ON ELM PLACE IN NUTLEY, NEW JERSEY, WHERE I GREW UP, THERE WAS A HOUSE AT THE BOTTOM OF THE STREET, RIGHT NEXT TO A LITTLE BROOK. I REMEMBER IT DISTINCTLY BECAUSE EACH SUMMER AND AUTUMN, THE SIDE YARD WAS FILLED WITH THE MOST AMAZING FLOWERS. THE GARDEN WAS SURROUNDED BY A WHITE PICKET FENCE; ON THE OTHER SIDE OF THE NARROW GATE GREW THE INCREDIBLE, COLORFUL BLOOMS MY FATHER TOLD ME WERE DAHLIAS.

The couple who lived there were proud of their dahlias. They knew each by name, and sometimes, if I asked nicely, they would let me into the garden to gaze with awe at the “dinner plates,” the “pom poms,” the “miniatures,” and the “cactus.” It was a riot of color, the plants staked upright to keep the blooms from sagging to the ground, and the garden was neat as a pin. I vowed to have a dahlia garden, sometime, somewhere.

That garden did not happen at Turkey Hill, in Westport, Connecticut, but I was inspired there, too, by two local gardens. One was on Maple Avenue, where a friend, an unlikely gardener, grew magnificent dahlias of all types in her side yard. That garden, also very neat and orderly, was regimented with 2-inch-by-2-inch stakes lined up geometrically, and tied with a spider net of twine to keep the dahlias straight as soldiers. And then I went to view the dahlias of the potter and artist Frances Palmer in nearby Weston, who had transformed an unused tennis court into her dahlia garden. Those exuberant flowers inspired her pottery with their distinctive shapes and textures, and again I vowed to create a dahlia garden of my own.

Finally, I did, and in the most wonderful locale: the cutting garden of Skylands in Maine. There, behind a lattice garden fence, 10 feet tall, protected from the rampant deer and porcupines, I planted my dream dahlias—the creams, the apricots, the pale pinks, the lavenders, the striped, and the splashed—from tiny to huge in size. And I realized why I had waited so long. Dahlias are so much better in a place of their own, in a garden where stakes and ties and narrow paths for grooming and cutting are permissible. These things are necessary to grow dahlias successfully, yet not very acceptable in formal borders or viewing gardens.

I have had the chance to get to know many of the country’s best dahlia growers and learned much about how they care for and nurture their plants. I am still smitten with the giant 10- to 12-inch varieties, but I also like the easier-to-arrange smaller types, which come in such unusual sizes and formations. There are so many kinds that oftentimes it is difficult to comprehend that they are all dahlias! In arrangements, I prefer a profusion of all dahlias, of many types and colors. Kevin, on the other hand, will show off just two or three specimens, floating them in a shallow bowl, or more in a bouquet of mixed blooms and greenery. In any event, dahlias, like sunflowers and rudbeckias, fill an important need in any gardener’s garden. They are productive and useful from late summer until late fall, when most other garden flowers have already faded and disappeared from the landscape.

A considered arrangement can extend a sense of place. At Skylands, Kevin took his cues from the Josephine II black and gold lacquered papier-mâché table with mother-of-pearl inlay that the flowers would sit upon, and the elegant Chinese screen that served as its backdrop. He placed a flower frog in a copper bowl and built his exuberant yet refined dahlia study in red, orange, and yellow, making use of the warm color palette from spiky ‘Ferncliff Prelude’ all the way to the dark-red ‘Ferncliff Ebony’. “I pick a dark flower in the palette and place it deep within the arrangement,” he says. “Dark colors give the eye somewhere to fall into, drawing the gaze inward.”

Use coordinated dahlia blossoms or one large dinner-plate variety to construct a floating arrangement that is as much about the vessel display as it is the flowers. Working with a palette of pink for a dinner at Skylands (which included a pink granite dining table, pink Venetian glasses, and pink linen napkins), the pink and pinkish-yellow ‘Jane Cowl’ dahlias picked up on the undertones of the twentieth-century Indian brass bowl and serving tray.

GROWING & ARRANGING

THE GENUS DAHLIA, NAMED FOR EIGHTEENTH-CENTURY SWEDISH BOTANIST ANDREAS DAHL, OFFERS A VAST VARIETY OF BLOOMS—FROM FLOWER HEADS THE SIZE OF DINNER PLATES TO TINY TIGHT-PETALED POMS. THEY APPEAR IN COLORS FROM PALEST PINKS TO DEEP BURGUNDY BLACKS. SUCH VERSATILITY INSPIRES ALL KINDS OF CREATIVE POSSIBILITIES, IN THE GARDEN AND IN THE VASE.

In the garden at Skylands, we grow many different single- and double-flowering varieties. Here a ball-shaped pom-pom dahlia, ‘Ferncliff David Digweed’, grows up to about 4 feet tall in the garden beds. The dahlias’ usefulness as a flowering bush includes its ability to conceal large holes in a garden, especially in the late summer and fall when the rest of the garden may be past its prime.

Dahlias grow tall and proud, and to keep them that way, it’s a good idea to support them with stakes. You can use bamboo or wood, as long as it’s sturdy. In the dahlia beds at Skylands, a combination of cages, stakes, and a “cat’s cradle” of twine allows the flowers to grow without drooping.

HOW TO GROW

Dahlias are easy to grow in most parts of the United States, but proper spring planting and winter storage are essential for success. Colors include white, pale to bright yellows, orange, bronze, pinks and purples, and all shades of red from fire engine to velvety maroon. Many gardeners also love their striking bicolors and variegates, such as ‘Union Jack’ and ‘Deuil du Roi Albert’, or those that boast colorful foliage, such as ‘Bishop of Llandaff’, a hot red-orange variety with purple-bronze foliage.

ZONE Dahlias are hardy in Zones 8 to 10, and can survive winters in Zone 7 with a thick layer of protective mulch. In these warm climates, dahlias can act as perennials, though some gardeners still dig them up each fall in order to ensure their vitality. My farm at Katonah is on the border of Zones 5 and 6, depending on the year, and Skylands (in Maine) is even colder; in areas like these, dahlias should be treated like annuals. We dig them up and store them with the first frost, then replant each spring (see Storage, this page).

SOIL Dahlias need well-drained soil that’s rich in organic matter, in an area that’s sheltered from strong winds. Dahlias prefer a soil pH of 6.5 to 7.0, and the soil needs to be at least 60 degrees before planting, which is usually in late May or early June, depending on the region. In my gardens, we primarily amend the soil with farm-made compost, and add a dry, balanced fertilizer.

LIGHT Choose a location that gets a good amount of direct sunlight. My dahlias, like any in the Northeast, need full sun; dahlias in Southern regions can handle afternoon shade as long as they get at least six to eight hours of sunshine daily.

CHOOSING Dahlias for planting arrive in tuber form, a plant organ system that comes in all shapes and sizes depending on the variety. Tubers should be firm and dry, with no soft spots or disease. Once planted, the tuber will grow roots, which produce additional tubers (which can later be divided and replanted; see this page), and the flower will sprout from the eye, or growth point.

PLANTING You can get a head start by potting the tubers indoors about a month before it’s time to plant. Or you can skip this step and head outside once the soil is warm enough (at least 60 degrees). To plant, dig a hole 4 to 6 inches deep, set the eye of the tuber so it sits about 2 inches below the surface of the soil (whether in a pot or in the ground), then fill in with more soil and press down to remove any air pockets. Water the potted shoots thoroughly and place them on a warm, sunny windowsill until the weather is warm enough to transplant them outdoors. If planting larger varieties, such as ‘Jane Cowl’, be sure to drive stakes into the ground, 18 to 36 inches apart, ahead of planting in order to support the plants as they grow (see Staking, below). A full-size dahlia plant can easily fill a spot several feet across, so plan accordingly and make sure your dahlias will have sufficient room for air to circulate around them.

If you’re in a warmer zone and your ground doesn’t freeze as deep as the tubers are planted, they can stay put year-round. You may want to dig them up every couple of years, however, to check whether they need dividing. When a clump of tubers has appeared where one used to be, it’s time to take pruners or a sharp knife and do some separating. Keep the neck of the tuber intact, and, when divided, make sure each piece has an eye. A single tuber can produce five to twenty additional tubers in a year of growth, making dahlia plants an excellent investment.

WATERING Tubers store the root systems, so do not water them too much at once before shoots emerge, to avoid possible rot. Understand the look and feel of your soil to judge whether the plant needs additional moisture; if hard-packed or slow-draining, water more gradually. Do not water until growth appears above the ground, when plants are 6 to 12 inches tall. Once plants are established, a deep watering twice a week will get them through summer dry periods.

FERTILIZING A week or two before planting, mix well-rotted manure, compost, or 5:10:10 fertilizer into the soil. At Skylands, the dahlias receive liquid fertilizer through the irrigation system every month. If you have a drip system or hoses set up, consider incorporating periodic fertilization. If you’re more concerned with foliage than flowers, use a high-nitrogen fertilizer, which will promote foliage but reduce flower yield.

STAKING Most large dahlias need support via staking, as the flower heads can become too heavy for the stems. Before planting (to avoid injuring tubers), drive a heavy stake at least a foot into the ground, then plant tubers about 3 inches from the stake. As the dahlia grows, tie off every foot or so. At Skylands, we pound gray 1 by 1 wood stakes in between the plants, 2½ to 3 feet apart, with jute twine spiderwebbed down the row to help support the branches and blooms as needed.

PRUNING Deadheading is the key to keeping dahlias blooming. When your plant is 6 to 8 inches high, remove all but the strongest couple of stems. Prune deeply so that the plants do not become top-heavy and prone to breakage. To channel the plant’s energy and encourage maximum bloom size (a must for show-quality entries), pinch off all of the smaller buds as they grow. To encourage a few big blooms at Skylands, we pinch the smaller buds lightly but not religiously.

STORAGE In colder climates and when treating dahlias as annuals, proper storage of the tubers between seasons is crucial. After the first frost, cut stems about a foot above the ground and carefully dig around the tuber clumps. Stay about a foot away from the stem when digging, to avoid bruising or spearing the tubers. Work slowly and gently knock off excess soil from the clumps. Then cut stems to a few inches, wash off the soil, and leave the tubers to dry, stems down. Set them in an airy place (not in the sun) to dry, until the soil easily shakes off. We dry our tubers indoors on racks for a few weeks, shaking off excess dirt and checking for rot and disease. Then we place them loosely in burlap sacks and store them in a dry attic or basement corner for the remainder of winter. You can also place the tubers in shallow cardboard boxes, covered with slightly damp sawdust, vermiculite, or a mixture of dry soil, peat, and sand, so only the stem pokes out. Some experts trim off the fine roots, too, and dip tubers in antifungal powder (such as lime and sulfur dust) before storing. The ideal storage temperature is 40 degrees, although anything between 34 and 50 degrees is acceptable.

Check the tubers’ health every few weeks through the winter, and quickly discard any that look moldy or soft. Tubers that look shriveled should be misted with water until the sawdust is barely damp. If any tubers are slow to recover, remove them from the box for a few days and mist with warm water a couple of times. Even the most experienced gardeners lose a percentage of their tubers each year, so don’t let it discourage you.

TROUBLESHOOTING Dahlias shorter than 8 inches are vulnerable to slugs and snails; pick them off if they appear. Control heavy aphid, earwig, or spider mite infestations with insecticidal soap. If dahlias show breakage and wilting, borers may be present. Deter them by keeping away weeds and cutting off any larvae-infested stems. Borers are an internal parasite, so spraying won’t always remedy the situation. If they get too aggressive, simply remove the branches entirely. If you have leaf-hoppers, which feed on sap, spray plants with one tablespoon isopropyl alcohol mixed in one pint of insecticidal soap. Spider mites are especially tricky during hot, dry weather; spray undersides with neem oil or a jet of cold water. If powdery mildew appears (a whitish coating on the leaves), spray with wettable sulfur or another fungicide, and give plants more space for air circulation. Mildew, fungus, aphids, and whitefly are more likely in warm, damp weather. In Katonah and at Skylands, our dahlias are fairly disease free, but we spray them appropriately as needed.

In the oak-paneled flower room at Skylands, several just-picked dahlia varieties—along with snapdragons and scabiosas—are stored in galvanized metal containers of water. The flower room (a.k.a.“Kevin’s office”) is well equipped with a refrigerator, a long counter, cutting tools, flower frogs, traditional floral buckets, and a variety of vases and other vessels.

Kevin surveys the morning’s haul before he begins designing the day’s arrangements.

HOW TO ARRANGE

CUTTING Flowers that are cut in full bloom tend to last the longest, but buds work well in arrangements, too. In general, select blossoms that are not too closed or too open. Make sure the petals don’t come off easily, and strip the leaves from the stems. Use a sharp knife and place the cut stems directly into water. Dahlias can continue to bloom after cutting, so be judicious about where you’re snipping on the plant. Kevin advises taking an occasional risk when cutting dahlias—consider a stem with a big flower and two buds; those buds may still bloom in the vase, or they may not, and that’s part of the fun of including them.

MAINTAINING To get the most out of your cut flowers in a cool climate, place them in very hot water in the vase and let it cool. Warm water transfers up the stem faster, and is especially important with dinner-plate dahlias to ensure the big blooms don’t become thirsty when freshly cut. Keep the cut flowers in fresh, clean water, changing it regularly to ward off bacteria. If the petals brown, simply remove and discard them. Dahlias can be long-lived because they are late-summer blooms—they’re hardy enough to withstand a few cold nights.

ARRANGING Because dahlias come in all sizes, a variety of containers work well, from bud vases to punch bowls. A flower can stand alone as a single bloom, or settle nicely in a ginger jar with a mixture of sizes and forms. Like lilacs, they yield many flowers per plant, allowing for voluminous arrangements even from a small garden.

Dahlias can make beautiful foundations for seasonal fall bouquets, provide bright pops of color against darker-shaded autumnal foliage, or set a moody tone with their deeper, burnt hues. Try a mix of cultivars, such as round ‘Paul Smith’, scarlet ‘Arabian Night’, or flame-colored ‘Fire Magic’. Beginning in late summer, dahlias pair nicely with plentiful chrysanthemums, chocolate cosmos, red and yellow zinnias, and sunflowers. Add texture with bright-red viburnum or Skimmia berries in a bouquet of copper-colored ‘Autumn Joy’ and russet dahlias, or surround bronze ‘Pamela’ dahlias with burgundy astilbe, velvety roses, and a border of red berries.

Dahlias are very exuberant flowers, so it is better to get playful with your arrangements than to try to control their shape in a static bundle. Use one color as a base, playing with another on top. A tape grid (see this page) can work wonders with large, top-heavy dahlia blooms, helping to create volume, lend balance, or keep the flowers stationary in a shallow vase. You can also cut the stems on a slant, about an inch below the bloom, and float in tepid water. Try setting a flower upon the rim of a teacup; leave an inch of stem attached so the flower can drink.

The grand scale of dahlias invites you to arrange them in vessels that are larger and heavier than those you’d use with more delicate flowers. Take this tall, hefty Old French glazed earthenware crock that holds an oversize gathering of big late-summer ‘Prince Noir’ and ‘Ferncliff Ebony’ blooms, along with shoots of awakening buds. “The buds act as sparks,” Kevin says, “so you don’t drown in the mass of all these flowers.” It’s just right for the 14-foot-long kitchen table at Lily Pond in East Hampton.

A nineteenth-century tole tea tray holds all of the elements of an arrangement. The stems have been sorted and trimmed and extraneous leaves removed. This allows for a clearer focus on the composition from the outset.

Kiwi leaves and unripened berries from the garden at Skylands add a sweeping gesture and a dose of green to this dome of color-saturated blood-red ‘Juanita’ (a South African variety) and bicolor ‘Kaiser Wilhelm’ dahlias. The visual pop of brightness helps the eye appreciate and take in the deeply hued blossoms. An ornate Edwardian mirrored silver plateau further elevates the pressed-glass footed compote, turning a grand vase into a grander centerpiece for the room.

A large Staffordshire soup tureen, fitted with a giant flower frog, holds a stunning arrangement of three unusual fall blooms: ‘Princesse Louise de Suede’ striped dahlias in orange and white, papery Chinese lanterns stripped of all leaves, and dill turned to yellow flower heads. Though it was originally intended for the dinner table in a different context, the tureen offers the wide mouth and sense of abundance required for this arrangement. “This is particularly good as a table centerpiece,” Kevin says, “because the flowers are at eye level and offer a close-up view of the beautiful petal structure.”

A great way to highlight one gorgeous flower is to gather several of its blooms to form a peak in a wide-mouthed vessel such as this segmented, three-tiered brass bowl, set on a mirrored faux-bamboo platter. This deceptively simple arrangement combines striped and solid dahlia varieties in oranges and reds with an exclamation point of yellow-and-burgundy-striped petals at the center.

Lit up by the golden glow of autumn sunlight, the rich shades of burnt orange and rosy yellow complement the ‘Ferncliff Ben Huston’ dahlias and ‘Autumn Joy’ sedum. Studded with large, leathery leaves and delicate irises, this green and russet–hued arrangement mixes textures to great effect, with silky petals and rounded edges situated comfortably alongside fizzy flower clusters and rough-edged foliage.

An early autumn arrangement combines late-season ‘Snoho Doris’ dahlias with ‘Chantilly’ snapdragons and Gomphocarpus physocarpus. In a stout faux bois cylinder, the bouquet evokes a woodland theme. To construct it, Kevin started with a base of dahlias, then added the tall, spiky Gomphocarpus. The vertical lines help expand the scale of the arrangement without adding too much density, for an end result that combines all the beautiful last gasps of the flowering season.

For this centerpiece, a single ‘Jane Cowl’ dahlia bloom was snipped and set in the Chinese brass and silver–handled bowl embellished with a dragon. The blossom is positioned to look like an extension of the dragon. When setting a flower in a floating arrangement, be sure to leave an inch or so of stem attached so the bloom can continue to drink. “There’s a level of sophistication to dahlias,” Kevin says. “They’re so beguiling, they can do anything. It’s a flower that is just as beautiful in bud form as in full bloom, and you can make a big impact with just one blossom.”

The inherent drama of dinner-plate dahlias (here ‘Jane Cowl’) allows for simple, deliberate arrangements. Each miniature cylinder, fused together within the clear glass vase, holds an individual stem, precisely trimmed to the appropriate height. With the vase providing support, the flowers can remain upright and showy—ready to embrace their well-deserved spotlight.