Dahlia Care

When to Plant

Plant after the last frost, once soil has warmed. Choose a location with full sun. Blooms from late summer through fall.

Soil

Amend your soil with quality compost. Peat moss can be used to loosen heavy clay soils and improve drainage. I add bone meal to each planting hole. Mix amendments into the soil. 

Planting and Supporting 

Plant each tuber 4-6 inches deep. Place horizontally with the eye facing up. Space 12 inches apart.

There are many methods of staking and supporting dahlias. If you choose to place individual stakes, do so before back-filling soil. If you place supports later in the season you risk puncturing or damaging tubers. 

Apply slug bait at the time of planting and throughout the growing season. Slugs and snails can destroy the tiniest of sprouts before gardeners realize they’re there. It comes in liquid or pellets and will indicate on its label whether it is safe for use with children and pets. I personally use Sluggo Plus, an organic choice that also protects from earwigs.

Watering 

Dahlias should not be watered until green growth pokes through the soil. Once growth appears above the ground, water deeply two to three times a week. Over watering can lead to tuber rot.

Pinching and Disbudding

When dahlias are about a foot tall give them a hard pinch. Pinching back, or cutting 3-4 inches of the center stalk, creates bushier plants with more blooms. To encourage large blooms, consider disbudding your dahlias. Disbudding involves removing the two smaller buds next to the center bud of a flower cluster. This encourages fewer but larger flowers per stem. 

Harvest flowers often and deadhead spent blooms for continued flower production. 

Fertilizing

Dahlias benefit from low nitrogen liquid fertilizers. Apply after sprouting and then every 3-4 weeks from midsummer until early fall. Some gardeners chose to stop fertilizing once dahlias began blooming.

Overwintering or Storing

Dahlias are hardy in USDA zones 8-10 and can be cut back and left in the ground to overwinter. Zones 3-7 should lift and store dahlias during winter. I leave mine in the ground and protect with heaping mounds of compost and leaf mulch.

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