Larkspur
Seed # 145
Basic Information
- Seed Number
- 145
- Seed Name
- Larkspur
- Variety
- Giant Imperial
- Category
- Flower
- Plant Family
- Ranunculaceae
- Plant Type
- Annual larkspur (Consolida ajacis)
- Planting Method
- Direct Sow
- Seed Status
- In Seed Bank
- Created
- 2026-08-14 00:50:34
- Updated
- 2026-08-19 15:35:29
Planting Information
- Start Planting Date
- Apr 7
- Last Recommended Planting Date
- Apr 14
- Plantable Months
- April
- Indoor Start
- Not recorded
- Direct Sow
- Apr 7 – Apr 14
- Transplant
- Not Recommended
- Indoor Start Weeks Before Frost
- Not Recommended
- Transplant Weeks After Frost
- Not Recommended
- Germination Days
- 20–35 days
- Harvest/Maturity
- 98 days to bloom
- Succession Planting
- Not recorded
Growing Conditions
- Ideal Soil Temperature
- 50-55°F
- Planting Depth
- 1/8 in
- Plant Spacing
- 18 in
- Row Spacing
- 18-24 in
- Thin-To Spacing
- 18 in
- Sun Requirements
- Full sun
- Water Needs
- Water regularly during dry periods but avoid saturated soil
- Soil Preference
- Rich, well-drained soil; slightly acidic to slightly alkaline
- Minimum Container Size
- deep/heavy pot + support
- Plant Height
- 3-4 ft
- Perennial/Biennial Status
- Annual
- Container Friendly
- No
- Trellis/Support Needed
- No
- Frost Tolerant
- Yes
- Heat Tolerant
- No
- Drought Tolerant
- Yes
- Pollinator Friendly
- Yes
- Medicinal
- No
Garden Uses
Container Cut Flower Medicinal Pollinator Seed SavingCompanion Planting
| Plant | Relationship | Notes |
|---|---|---|
| China Rose | Good Companion | Not recorded |
| Rose | Good Companion | Not recorded |
| Rosehips | Good Companion | Not recorded |
| Sweet William | Good Companion | Not recorded |
Storage
- Seed Source/Brand
- Select Seeds; Ferry-Morse; NC State Extension; Utah State Extension
- Packet Year
- Not recorded
- Quantity Notes
- Not recorded
- Purchase Date
- Not recorded
- Expiration Year
- Not recorded
- Storage Box
- Not recorded
- Container
- Not recorded
- Envelope
- Not recorded
- Row
- Not recorded
- Slot
- Not recorded
- Storage Notes
- Not recorded
Notes
Original Planting Method: Direct sow preferred. Seed germinates best in cool conditions; cover seed because darkness helps germination.
Original Start Planting Date: Mar 25 – Apr 10
Original Last Suggested Planting Date: ~May 1 spring; optional late-fall dormant sow
Outdoor / Direct Sow / Transplant Window: Direct sow ~Mar 25 – May 1. Optional late-fall dormant sow after soil cools.
Days to Harvest / Bloom: ~14 weeks / ~95–105 days to bloom
Container Friendly: Yes; deep/heavy pot + support
Pollinator Friendly: Yes; bees and other pollinators
Medicinal / Herbal Use: No; do not use as home medicinal herb because larkspur is poisonous.
Succession / Reusable Notes: Two early sowings 2–3 weeks apart can extend bloom. Leave a few seed heads if you want natural reseeding.
Zone 6B Notes: Cool-season annual that performs well when sown before average last frost. Zone 6B summer heat eventually shortens display.
Companion Plants: Sweet William, poppies, bachelor's buttons, roses, other cool-season/cottage flowers
Avoid Planting Near / Watch Outs: TOXIC if eaten; unsafe for people, pets, and livestock. Dislikes hot, humid, waterlogged conditions; tall plants may need support.
Sources: Select Seeds: https://www.selectseeds.com/products/larkspur-giant-imperial-seeds | Ferry-Morse: https://ferrymorse.com/products/larkspur-giant-imperial-mixed-colors | NC State Extension: https://plants.ces.ncsu.edu/plants/delphinium/ | Utah State Extension: https://extension.usu.edu/pests/news/delphinium-larkspur-pests.php
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Zone 6B: Direct sow approximately 3-4 weeks before the May 5 last frost. Giant Imperial prefers cool spring conditions and performs poorly when establishment is delayed into hot weather.
Germination: Seed requires darkness for germination. Sow approximately 1/8 inch deep in cool soil. Germination may take 20-35 days.
Harvest: For fresh bouquets, harvest when approximately 2-5 florets on the spike are open. Flowers are also suitable for drying.
Seed Saving: Allow selected flower spikes to mature and seed capsules to dry. Giant Imperial readily self-sows when mature seed is allowed to fall.
Special Care: All parts of larkspur, including the seeds, contain toxic alkaloids and should not be eaten. Provide good airflow and avoid saturated soil to reduce fungal disease.
Research Source: Select Seeds — https://www.selectseeds.com/products/larkspur-giant-imperial-seeds — Consolida ajacis identity, annual habit, 3-4 foot height, full sun, rich drained soil, 1/8-inch depth, darkness requirement, 20-35 day germination, 14-week bloom time, direct-sow timing, spacing, water, pollinator attraction and cut-flower use
Research Source: Pinetree Garden Seeds — https://www.superseeds.com/products/giant-imperial-mix-larkspur — cool 50-55°F germination conditions and direct-sown larkspur culture
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