Dahlias

Planting dahlias

Plant tubers after the last frost when soil reaches about 60 F, laying them flat with the eye up. Stake tall varieties at planting to avoid piercing tubers later.

Planting details

• Plant tubers 4 to 6 inches deep
• Spacing: 18 to 24 inches
• Pinch the growing tip at 12 inches tall for more blooms

Growing requirements

Dahlias need full sun, fertile well-drained soil, and steady water once growth begins. Do not water tubers before sprouts appear; they rot easily.

Harvesting and care

Deadhead or cut blooms freely; flowering continues to frost. In cold climates, lift tubers after the first frost, dry them, and store frost-free over winter.

Common mistakes

• Watering tubers before they sprout, which rots them in the ground
• Planting in cold wet soil, which stalls or kills tubers
• Skipping stakes for dinnerplate types, which flop under their own blooms

Companion plants

Dahlias anchor cutting gardens alongside zinnias and cosmos, which share their sun and water needs and bloom over the same window.