Rocket Larkspur is an annual Delphinium that is native to Europe, but now grows as a wildflower in North America.
Latin
Delphinium ajacis
Family: Ranunculaceae
Difficulty
Easy
Season & Zone
Exposure: Full sun
Zone: 3-9
Timing
Sow indoors 8-10 weeks before planting out, so around late February to mid-March on the coast. Direct sow in early spring 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.