Annuals · Bulbs · Container Gardening

Start Dahlias Indoors for Earlier Blooms in the Garden

Even though spring is reluctant to make an appearance so far this year, there is plenty of gardening going on indoors at my house. Last weekend, seed starting continued and overwintered tubers of dahlias, freed from their winter hibernation in the basement, were planted.

Dahlias are flamboyant performers. Their flowers bloom in a rainbow of colors without pause from early summer until frost. There are cultivars available from tiny to towering. At this time of year, bags of dahlia tubers can be purchased at box stores, warehouse-type stores and garden centers for a few dollars. (Tubers are swollen parts of a root or stem that store food for the next growing season and produce buds for new plants.) Mine were free since they were overwintered from plants grown in containers on my deck last year.

Dahlia Tubers

If tubers are purchased now, they are ready to plant. Overwintered tubers can be separated first for more plants as long as there are at least three buds per clump.

Plant them several inches deep in moist potting mix, place pots under lights or in a sunny window, and water sparingly until new growth emerges. Begin feeding with a fertilizer higher in phosphorus and potassium than nitrogen, like 5-10-10 or 10-16-14, when the foliage is a few inches tall. In several weeks bushy plants will be ready to start spending some time outdoors to harden off, preparing for planting in the garden or containers after the danger of frost has passed.

Dahlia 'Goldalia Orange'
Dahlia ‘Goldalia Orange’

It will take until mid-summer for the first flowers to bloom, but patient gardeners can plant tubers directly in a sunny spot in the garden after the last frost date. Dig deep holes and amend the soil with organic matter before planting tubers with their points facing down six inches deep. Their spacing will depend on the type of dahlia. Large dinnerplate dahlias need considerably more room than the newer, smaller Dahlianova dahlias.

Dahlia 'Hypnotica Lavender'
Dahlia ‘Hypnotica Lavender’

Large-flowered dahlias need staking to hold up their enormous foot-wide blooms. Insert a sturdy stake when planting larger dahlias to reduce the chance of injuring tubers later.

Dahlia Flower Pink

Water thoroughly after planting and then wait until new growth appears before watering again. Begin fertilizing when the plant is a few inches tall. Do not overfeed – it will result in lush, but weak growth.

Planting dahlias from tubers is considerably less expensive than purchasing plants. Gardeners on a budget can have all the dahlias they desire without breaking the bank.

If you didn’t save tubers last fall, go out and purchase a few packs, pot ‘em up and garden with me!

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