36. SELF-SEEDERS! FREE FLOWERS! BE CAREFUL.

Self-seeding is a way Nature ensures that flowers keep returning. Self-seeders are plants that freely disperse their seeds to germinate and eventually pop up all over the place. Seed them once, and they return, via new seeds, each year. These self-sown plants sometimes grow in unwanted places, but it is relatively easy to transplant or remove them. Beginning gardeners can’t fail with vigorous self-seeders—they don’t require much, and they bring an element of surprise to your landscape.

Some gardeners frown on self-seeding flowers because their random appearances upset the orderliness of a flower border. Others embrace self-seeding because it is a gardening technique that works with Nature to develop a “cultivated wildness” and a less fussy garden. Self-sowers may be annuals, biennials, or short-lived perennials. You can sow the seeds directly onto the soil. After that, watch as Nature does her thing. Left alone, prolific seeders let you “intermingle” plants that flower and mature at different times, which creates interest throughout the year. To do this, let the seed heads of self-seeders ripen fully. Do not deadhead the flowers! The seed capsules dry out on the plant and eventually split open to release tiny seeds. You can harvest the ripened, brown capsules and scatter seeds wherever you want new flowers to grow. Some seedlings may be slow to emerge, and some may need a period of cold before they germinate. Patience is necessary.

Some annual flowers are prolific self-seeders. These can become invasive if you are not careful. But if you manage these seedlings, you will always have something in bloom with little effort. Annual self-seeders include the old-fashioned spider flower (Cleome), German chamomile (Matricaria recutita), bachelor’s buttons (Centaurea cyanus), tall verbena (Verbena bonariensis), sweet alyssum (Lobularia maritima), and love-in-a-mist (Nigella damascena). The same holds true for biennials and perennials such as foxgloves (Digitalis var.), bleeding heart (Lamprocapnos spectabilis), Lenten rose (Helleborus orientalis), white wood aster (Eurybia divaricata), columbine (Aquilegia), and forget-me-not (Myosotis sylvatica). Try the hardy perennial ‘Jackpot’ snow daisy (Tanacetum niveum ‘Jackpot’), for masses of white self-sowing flowers. Before sowing, make sure your choices are not listed as a noxious weed in your area.

Eastern red columbine (Aquilegia canadensis) is a short-lived native perennial with showy red-and-yellow nodding flowers with long narrow spurs. It blooms in late spring/early summer in sun to part shade. It likes well-drained but moist soil and grows 1 to 2 feet tall. Red columbine self-sows its abundant seeds, and new plants then pop up between rocks or in woodlands. Scatter columbine seeds in bare areas—it is deer and rabbit resistant. The cultivar ‘Little Lanterns’ is half the height of the regular species. Very attractive to hummingbirds. Zones 4–8.

The small, daisy-like flowers of forget-me-nots (Myosotis sylvatica) are rampant self-seeders. They are listed as a noxious weed in some Midwestern states so be careful with them. They thrive in moist areas with morning sun. They come in shades of blue, yellow, or white, often with yellow or white eyes. Forget-me-nots look best planted in groups in rock gardens, beds, or in borders. Zones 3–8.

‘Sweet William’ catchfly (Silene armeria) is a tough, hardy perennial that easily self-sows. It will pop up in the garden everywhere. It is native to Europe but has naturalized in parts of the United States. Its vivid rose-pink rounded flower clusters appear in summer on 12- to 16-inch-tall upright stems. It likes full sun with excellent drainage. It does not do well in high humidity and heat. Zones 5–8.