Garden Dahlia

Garden Dahlia (Dahlia pinnata) is the type species of the genus Dahlia, originating from Mexico and Central America. It produces single or double flowers in vivid, mixed colours and blooms prolifically until the first frost. A sun-loving annual in Nordic conditions, it thrives in well-prepared garden soil and rewards with a long cutting season. Frost-tender — plants must not be exposed to freezing temperatures.

Growing

Start seeds indoors 8 weeks before outdoor planting conditions are met. Sow 1.5 cm deep in trays or pots at a soil temperature of at least 18 °C; germination takes 5–15 days. Grow seedlings under good light to prevent legginess. Transplant outdoors once nights stay reliably above 5 °C and all frost risk has passed. Space plants 30 cm apart in a sunny, sheltered position with fertile, well-drained soil.

Care

Water regularly but avoid waterlogging — dahlias prefer evenly moist soil. Feed with a potassium-rich fertiliser once flower buds form to support bloom production. Pinch out the growing tip after the first few true leaves to encourage branching and more flowers. Stake taller plants with canes to protect against wind damage. Remove spent flowers promptly to extend the blooming period.

Harvest

Cut flowers when the outermost petals have fully opened and the bloom is firm — a half-open bud will not continue to develop in the vase. Harvest in the early morning with clean, sharp scissors, cutting stems as long as possible. Continue cutting regularly throughout the season; the more you cut, the more blooms the plant produces. Plants continue flowering until frost.

In the kitchen

Dahlia flowers are edible and can be used as a garnish on salads, desserts, and cakes. Petals add colour to summer plates. The tubers are also edible — similar in texture to water chestnuts — and can be roasted, boiled, or eaten raw in small quantities.

Storing

Cut flowers last 5–8 days in a vase of cool, clean water; recut stems at an angle and change the water every two days. Tubers dug after the first light frost can be dried for a few days, then stored in a cool, frost-free location (2–5 °C) in slightly damp sand or peat throughout winter. Check stored tubers monthly and discard any that show rot.