Dahlia Care

When to Plant

Dahlias are cold sensitive. They should be planted in spring after your last frost and once the soil has warmed. Chose a location with full sun (6-8 hours) and hold off on planting if a stretch of rain is predicted.

Preparing Your Soil

Amend your soil with quality compost. I've had great success with fish compost and a light application of bone meal. Peat moss can be used to loosen heavy clay soils and improve drainage. Be sure to mix all ingredients into the soil. 

Planting and Support Instructions 

Plant your tuber 4-6 inches deep with the tuber eye facing upwards. Allow at least 12 inches of space between tubers. Supporting your dahlias is important to their success. There are many methods of supporting dahlias. Whichever method you chose, place your support stakes at the time of planting before back-filling the dirt. If you place supports later in the season you risk damaging your tubers. 

Apply slug bait at the time of planting and throughout the growing season to keep slugs and snails from destroying plants. It comes in liquid or pellet form and will indicate on its label whether it is safe for use with children and pets. 

Watering Your Dahlias 

Dahlias should not be watered until green sprouts poke through the soil. Overwatering can lead to tuber rot, so hold off until growth appears above ground. Once growth appears above the ground, water deeply two to three times a week. 

Pinching Your Dahlias + Getting More (or Bigger) Blooms

When dahlias are about a foot tall give them a hard pinching. 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 is simply removing the two smaller buds next to the center bud of a flower cluster. This encourages the plant to put energy in fewer but much larger flowers. 

Harvesting flowers often and deadheading spent blooms also encourages dahlias to produce more blooms. 

Fertilizing Your Dahlias

Dahlias benefit from low nitrogen liquid fertilizers. Apply after sprouting and then every 3-4 weeks from midsummer until early fall. You may stop fertilizing once dahlias are blooming. Be sure to water your dahlias thoroughly before applying liquid fertilizer.

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.

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