How to Grow Delphinium

Rocket Larkspur is an annual Delphinium that is native to Europe, but now grows as a wildflower in North America. It is very easy to grow and will tolerate nearly any garden soil. Continue reading below for some tips on how to grow Delphinium from seeds.

Latin
Delphinium ajacis
Family: Ranunculaceae

Difficulty
Very easy

Season & Zone
Exposure: Full sun

Timing
Sow indoors 8-10 weeks before planting out. Or simply direct sow in early spring, when a light frost is still possible, or early autumn. Seeds take 14-28 days to sprout.

Starting
Just cover the tiny seeds. If starting indoors, vernalize seeds by planting them in trays in sterilized seed starting mix. Place these inside plastic bags and refrigerate for 2 weeks. Then place them in total darkness and maintain a soil temperature of 10-12°C (50-55°) until sprouted. Once sprouts appear, place below bright light. Space or thin to 30-45cm (12-18″) between plants.

Growing
Deep, rich, well-drained, slightly acidic soil. For the most bloom potential, water well throughout the season, and feed once in the early spring. Remove spent flowers immediately after the first bloom, and feed again. When new growth reaches about 20cm (8″) tall, cut back old growth completely.