PlantSowGrow
How to grow Larkspur (Giant Imperial Mixed)
Consolida ajacis
Tall, delphinium-like spikes in blue, pink and white — superb fresh or dried for cutting. All parts are poisonous if eaten.
At a glance: Sow mid March to mid May.
When to sow, plant and harvest
Timed for a typical UK garden (last frost mid-April). The app uses your own town's frost dates.
Growing Larkspur (Giant Imperial Mixed): what it needs
- Light
- Full sun · 6+ hours a day
- Watering
- Water in dry spells; pots daily in summer
- Soil
- Any well-drained soil
- Spacing
- 25 cm
- Height
- 90 cm
- In pots
- Grows well in containers
- Feeding
- Liquid feed every two weeks once flowering starts
- Hardiness
- USDA zones 2–11
- Difficulty
- Easy
Step by step
- Mid March – mid May · 4 weeks before the last spring frost
Sow Seeds Outdoors
Sow thinly where they are to flower, in a sunny spot, into raked, weed-free soil. Chill the seed in the fridge for a week before sowing; sow 0.5 cm deep where they are to flower.
- 14–21 days after “Sow Seeds Outdoors” · Early April
Check Germination
Seedlings should appear in 14–21 days. Keep the soil moist. If sown outdoors, thin them to 25 cm apart once they have two true leaves.
- 14 days after “Check Germination” · Mid April
Add Support
Push in canes or twiggy sticks and tie in stems before they flop.
- 69–99 days after “Check Germination” · Early June – early July
First Flowers — Deadhead Regularly
Snip off faded flowers every few days to keep new ones coming for months. Take a photo for your journal!
- Mid October – early November · around the first autumn frost
Clear or Collect Seed
When frost blackens the plants, pull them up for the compost heap. Leave a few seedheads first if you want to save seed.
