March is the time gardeners start dreaming about summer gardens full of blooms and color. Doug Tallamy’s research in residential gardening suggests cultivating gardens full of color, layers and diversity of plants with about 70% natives will provide necessary habitat, food and shelter for the native wildlife. Although native to the high plains of Mexico, Dahlias are members of the Asteraceae family (composite flowers), and are quintessential tubers of gardens in the Olympic Peninsula. Suzanne Eggleston, Jefferson County Master Gardener and dahlia enthusiast, says, “Dahlias are incredibly diverse in color, form, and petal arrangement. Bees love dahlias, they’re easy to grow, and yield beautiful blooms from midsummer through fall.” 

Tubers are swollen underground storage stems or rhizomes that provide nutrition while they are dormant. Because of their high nutrient content, many tubers, like potatoes, are grown for food. There are three important parts of the dahlia tuber: tuber, neck and crown. The crown is where the “eyes” or nodes are located, and from which shoots and stems will grow in the spring.

Planting and care

Eggleston advises that “it’s all about location, location, location” when it comes to successfully growing dahlias. They need between 6-8 hours of full sun in well-drained soils, and to be sheltered from wind. They prefer neutral to slightly acidic soil. 

“Select tubers that are firm to the touch and have multiple eyes that will turn into the stalks,” says Eggleston. “My rule of thumb is that it’s safe to plant tubers here anytime between Mother’s Day and Father’s Day.” Dig a hole 6-8” deep, add compost and a little bone meal, and mix into the soil. Then place the tuber horizontal with its “eye” up. Add a stake if the plant is not low growing (i.e., ‘Bambino’, and ‘Binky’) and will be more than 24” in height at maturity, taking care not to plunge the stake through the tubers. Use garden tape or twine to secure the plant to the stake as it grows. Eggleston checks daily for slugs as they adore dahlias. 

Hold off watering until sprouts emerge from the ground. Eggleston installed a drip irrigation system that deeply waters her dahlias 45 minutes at a time every 2-3 days in the growing season. She says she increases the frequency more during intense heat. If you want fabulous blooms, it’s a good idea to fertilize about once a month during the growing season as dahlias are heavy feeders. 

Eggleston’s vibrant garden of dahlias includes more than 30 different varieties. To support this gorgeous bounty, her husband installed two double “T” shaped support structures across the length of her dahlia beds. The wire is threaded through the Ts in two places to provide support on two sides of each plant at 2’ and 5’ high that benefit tall and dinner plate-size blooms such as ‘Brandon Michael’ and ‘Spartacus.’ Her dahlia showcase is surrounded by deer netting. “People always say that deer don’t eat dahlias, but that’s not true in my garden. The deer love the blossoms and buds.”

Dahlias as members of the family Asteraceae are pollen and seed producers. Open-centered dahlias (i.e., Collarette ‘Bee-yond’; Single ‘Bashful’ and ‘Golden hour’; and Orchid ‘Tahoma Moonshot’) are easily accessible for pollinators. To allow for more bushy growth in your dahlia plants, pinch out the center after the plant generates 3-4 sets of leaves. Dahlias bloom in sets of three; for bigger blooms, pinch off the two side buds. 

In an orchestra the melody (treble clef) is played by instruments like the violin and flute while the harmonic support of the bass clef is played by lower pitched instruments like cello and bassoon. Dahlias with flaunt, swagger, color and variety contribute to the harmonic support that is your garden. 

Dahlia viewing opportunities in summer

Master Gardener Demo Park, The Cup, Port Townsend

Port Gamble Gardens; post office

Swan Island Dahlia Festival, Canby, OR: August-September

Ask a “Master Gardener” plant clinics are held at the Charles Pink House on the first Tuesday of the month from 12:00 — 2:00 running from January to December at Port Townsend Library. 

Michele Koomen, a volunteer for the Master Gardener Program since 2024, serves as a community educator in gardening and environmental stewardship.