Larkspur in Zone 5a & 5b
Consolida ajacis
Yes, larkspur grows in zones 5a and 5b. Plant it outside Apr 12–Apr 19.
When to plant larkspur in zone 5b
Zones 5a and 5b share the same average frost dates, so this page covers both.
Method: Direct sow: Direct-sow outside. It doesn't transplant well, or doesn't need the extra time indoors.
| Start indoors | Not typically started indoors |
|---|---|
| Direct sow / transplant outside | Apr 12–Apr 19 |
| Estimated bloom | Jul 16–Jul 23 (~95 days after direct-sowing) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 3-4 ft.
Plant alongside it in zone 5b
These go outside within two weeks of larkspur in zone 5b, so one planting day can cover them.
- Bleeding HeartApr 12–Apr 19
- Penstemon (Beardtongue)Apr 12–Apr 19
- Black-Eyed SusanApr 19–Apr 26
- Clarkia (Farewell-to-Spring)Apr 19–Apr 26
- Cynoglossum (Chinese Forget-Me-Not)Apr 19–Apr 26
- Phacelia (Lacy Phacelia)Apr 19–Apr 26
Larkspur is one of the few flowers on this site that flatly refuses to be transplanted. It has to be direct-sown, and the seed won't germinate at all unless it's cold and kept dark, which puts it on the opposite schedule from most annuals people start indoors under lights. Get the timing right and it rewards you with tall, dense spires of bloom; get it wrong and the seed just sits in the ground doing nothing.
How larkspur fits zone 5's season
Zone 5b's frost-free window runs about 148 days, from May 10 to October 5. Larkspur needs about 95 days from sowing to first bloom.
Larkspur planting windows in every zone
Zone 5b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Bloom |
|---|---|---|---|
| 2a & 2b | Not usually | Apr 22–Apr 29 | Jul 26–Aug 2 |
| 3a & 3b | Not usually | May 2–May 9 | Aug 5–Aug 12 |
| 4a & 4b | Not usually | Apr 17–Apr 24 | Jul 21–Jul 28 |
| 5a & 5b (your zone) | Not usually | Apr 12–Apr 19 | Jul 16–Jul 23 |
| 6a & 6b | Not usually | Mar 28–Apr 4 | Jul 1–Jul 8 |
| 7a & 7b | Not usually | Mar 13–Mar 20 | Jun 16–Jun 23 |
| 8a & 8b | Not usually | Feb 25–Mar 4 | May 31–Jun 7 |
| 9a & 9b | Not usually | Jan 18–Jan 25 | Apr 23–Apr 30 |
| 10a & 10bFall window | Not usually | Sep–Jan | ~95 days after direct-sowing |
Bloom dates are about 95 days after the sow or plant-out date.
Zone 2 sows before zone 3 here, which looks wrong and is not. USDA zones rank winter cold, not season length, and zone 2 is mostly interior Alaska, where hard winters come with warm summers. More on what a zone measures.
Good companions
No well-established companions for larkspur.
Where to buy larkspur seeds
Botanical Interests · True Leaf Market · High Mowing Organic Seeds (each supplier's larkspur seeds)
Varieties we recommend, and where to get them:
- Misty Lavender: Johnny's describes pearly gray-lavender blooms, identical in their trials to the heirloom 'Earl Grey', on the same 9-12 inch flower spikes as QIS. Buy: Botanical Interests Full notes
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing larkspur" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 5b calendar · Plan your beds in the Garden Designer →
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Growing Larkspur in USDA zone 5b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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