Growing Tips: Dahlia

Quick Reference:

Annual, a plant that completes it’s life cycle in one season. Tubers may be dug before the first frost in the fall for bloom a second season. Germinates in 5 to 10 days at an optimum soil temperature of 75 degrees F. Cover seed with 1/8 inch fine soil spaced ½ to ¾ inches apart. Ideal spacing in the garden is 12 to 16 inches. Plant height: 12 to 16 inches.

When and where to plant:

In Alaska it is recommended that dahlias be started indoors 6 to 8 weeks before the last frost for bloom over a long season. Fill a container that has drainage holes with a sterilized potting soil, sprinkle seed on soil surface, cover seed with fine soil, water well for good seed-soil contact and keep moist at all times until seedlings emerge. When seedlings show their first green leaves, water with a liquid solution of plant food. Soon after the seedlings have their first true leaves transplant to individual plastic pots, water with a liquid solution of plant food every two weeks and grow in a sunny area until the garden is ready. Select a sunny location with rich, well drained, moist soil, enrich with plant food and organic matter and transplant seedlings to the garden after last frost.


Keep well watered and fertilized. Cut blossoms to prolong bloom season.


Tubers are produced during the first season and may be dug in the fall before they freeze. Store tubers over winter in a plastic bag partially filled with dry peat moss and kept in a heated cool area. Plant tubers in spring for early bloom the second season.