Fashionably Late Flowers
They spend the first half of summer waiting in the wings. Then—pop!—dahlias unfurl their showy blossoms just as summer’s heat leaves most garden perennials in faded tatters. With their fanciful forms and fabulous hues, they’re a surefire hit for anyone looking to give waning beds a color boost.
Shown: A parade of brightly hued dahlias creates an eye-catching display.
Buy Potted Dahlias Now
That’s one reason these old-fashioned favorites have stood the test of time. “They were the ‘it’ flower from the mid to late 1800s and wildly popular again in the early 1900s,” says Scott Kunst, owner of Old House Gardens, a mail-order nursery specializing in heirloom plants. They’ve been a staple of cutting gardens and cottage-style plantings ever since, thanks to their long-lasting blooms and easy-care nature. While spring is the time to plant their potato-like tubers, it’s not too late to buy potted dahlias at garden centers to perk up your yard. Think of these dahlia varieties as alternatives to end-of-season regulars, such as chrysanthemums and fall-flowering asters.
The flashy dahlia family includes thousands of named varieties, most of them falling into 19 categories. Types are designated by flower shape, from the miniature pompon and the daisy-like single to the spiky cactus bloom. Traces of the dahlia’s wildflower past can be seen in older varieties, including the buttercup-like ” and the scarlet ‘Bishop of Llandaff.’ Recent releases, such as the candy-colored ‘Eden Talos’ and the ruffled ‘Leslie Renee,’ have more formal shapes, with the sturdy stems and perfect symmetry that garner blue ribbons at garden shows today.
Pollinator Bait for Edible Gardens
Dahlias mingle well with other colorful late-summer perennials, such as coneflowers and sedums, and add beauty to edible gardens, where they attract pollinators. Among the most spectacular are the dinner-plate dahlias, with flowers up to 16 inches wide. These top-heavy charmers hold their own beside sunflowers, amaranths, and other big bloomers. All dahlias die back during their off season, however, leaving bare spots. “In a border, it’s best to sprinkle dahlias here and there, rather than planting them in patches,” says flower farmer Diane Szukovathy, who is based in the state of Washington.
Need-to-Know Dahlia Basics
Growing them is relatively easy, if you know a few basics. Natives of Mexico, they thrive in rich, well-drained soil and require lots of sun. Because they’re cold-hardy only in Zones 9 to 11, gardeners in frigid regions often treat dahlias as annuals, though they can be dug up and overwintered. Tubers should be placed directly in the ground in late spring, after the soil warms up, about the same time you’d set out tomatoes. You can also give them a head start indoors, potting them up four to six weeks before the last expected frost. Don’t water until after the first leafy shoots emerge, however, since soggy soil causes tubers to rot. Dahlias taller than 3 feet need staking, so set up bamboo poles when you plant to avoid disturbing their roots later on.
Deadheading a Must
To encourage blooms, water regularly once they’ve leafed out, and apply a monthly dose of low-nitrogen fertilizer, starting shortly after planting and ending with a final feeding in mid-August. For a compact plant with lots of flowers, Hans Lange-veld, co-owner of Longfield Gardens, recommends pinching off the first bud on the center shoot, just below the third set of leaves. “This keeps the plant from putting all its energy toward producing just one flower,” he says. And, of course, deadheading is essential. Dahlias are cut-and-come-again perennials, so if you’re not regularly harvesting bouquets, be sure to remove spent blooms. Then they’ll give encore performances well into fall, until a good hard frost ends the show.
How to Dig Up and Overwinter Dahlias
If you live in Zones 2 to 8 and want to keep your prized specimens blooming year after year, you can dig them up and keep them in a cool, dry spot. Follow the steps below, and you’ll have tubers ready for planting come spring—and likely a few extras to share with friends.
Cut off the stalks two weeks after the first hard frost. Leave roughly 6 inches of stem intact. Use a shovel or a pitchfork to gently lift the tubers from the ground, being careful not to break their stems.
Rinse off caked-on soil and allow the tubers to air-dry in a sheltered spot for 24 hours. Then place them in crates or cardboard boxes lined with 10 to 12 sheets of dry newspaper.
Cover the tubers with slightly dampened peat moss, sand, sawdust, or wood shavings. Store in a cool, dry place, such as a shed, an unheated basement, or a garage. Too-warm tubers shrivel; if too cold, they freeze or rot. Check them monthly and relocate if necessary.