Larkspur Growing Guide
Growing Larkspur is easier than you think. This guide walks you through everything you need — from planting your first seed to harvesting.
At a Glance
Difficulty
Easy
Category
Flower
Sun Exposure
Full Sun
Frost Tolerance
Frost Hardy
Cold Hardiness
Survives to -12°C
Plant Family
Ranunculaceae
Growing Season
Cool Season
Plant Lifecycle
Annual
Also grows well as
How to Start It
★ Recommended for beginners
Scatter seed where it's to grow, in autumn or the first workable days of spring — the cold spell triggers germination. Thin the seedlings; don't try to transplant them.
The annual cousin of delphinium, giving the same elegant tall spires of (often blue or purple) flowers in early summer, but from a packet of seed. Two things matter: it needs COLD to germinate, so sow in autumn or as early in spring as the soil can be worked; and it dislikes root disturbance, so sow where it's to flower. It self-sows reliably once established. A cottage-garden and cutting-garden favourite. All parts are toxic if eaten.
When To Start
First Chance to Plant
—
Last Chance to Plant
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When should you plant Larkspur?
Your planting dates depend on your local climate. Sign up and add your location to unlock personalized dates.
Your Larkspur Planting Window
Start planting
May 15, 2026
Last chance
Sep 10, 2026
The Journey Ahead
Larkspur's Lifecycle
Seedling
Mature Plant
Seed Production
Step 1
Prepare Your Space
1 cm
Seeding Depth
20 cm
Plant Spacing
30 cm
Row Spacing
Vertical Growing
No.
Succession Planting
No.
Good Companions
Bad Companions
Step 2
Planting & Sprouting
Expect sprouts in 14–28 days
Growing Tips
- 1Sow cold and sow in place — those two rules unlock easy larkspur.
- 2Full sun and free-draining soil suit it; it's a cool-season flower that finishes as the heat arrives, so get it in early.
- 3Thin seedlings for sturdy cutting stems, support tall varieties, and let some seed drop for a self-renewing patch.
- 4Keep the toxic foliage and seeds away from children and pets.
Seedling Phase
Step 3
Growth & Maturity
100 cm
Mature Height
25 cm
Mature Width
Pests to Watch For
Diseases to Watch For
Mature Plant
Step 4
Harvesting
When to Pick
Spires bloom early summer; cut or deadhead to prolong, leave some to self-sow
How to Harvest
- 1Cut spikes for the vase (or for drying) when about half the florets are open.
- 2Deadhead spent spires to encourage side-shoots and a longer display — but leave a few to ripen seed if you want self-sown plants next year.
- 3Tall stems may need light support in exposed spots.
- 4Plants fade as summer heat builds; pull them then, and the dropped seed carries on.
Step 5
Saving Seeds
How to Save Seeds
Let the pods dry and brown on the stalk, then shake out the black seeds. Easy to save, and it self-sows generously.
Seed Production
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