Lupine in Zone 5a & 5b
Lupinus spp.
Yes, lupine grows in zones 5a and 5b. Plant it outside Apr 26–May 3.
When to plant lupine 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 26–May 3 |
| Estimated bloom | Jul 15–Jul 22 (~80 days after direct-sowing) |
Spacing: about 2 square feet per plant (square-foot-gardening spacing). Mature height: 2-4 ft.
Plant alongside it in zone 5b
These go outside within two weeks of lupine in zone 5b, so one planting day can cover them.
- Agrostemma (Corn Cockle)Apr 26–May 3
- AstilbeApr 26–May 3
- Bachelor's Button (Cornflower)Apr 26–May 3
- Basket-of-GoldApr 26–May 3
- Bupleurum (Thoroughwax)Apr 26–May 3
- CalendulaApr 26–May 3
Lupine is a nitrogen-fixing legume, but don't expect a quick soil boost from it. That nitrogen only becomes available to other plants once the foliage and roots break down, not while the plant is actively growing. It's grown here mainly for its tall, dense spires of pea-like blooms, and it has a strong climate preference worth knowing before planting: it wants mild summers and struggles badly in low-desert heat.
How lupine fits zone 5's season
Zone 5b's frost-free window runs about 148 days, from May 10 to October 5. Lupine needs about 80 days from sowing to first bloom.
Lupine 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 |
|---|---|---|---|
| 4a & 4b | Not usually | May 1–May 8 | Jul 20–Jul 27 |
| 5a & 5b (your zone) | Not usually | Apr 26–May 3 | Jul 15–Jul 22 |
| 6a & 6b | Not usually | Apr 11–Apr 18 | Jun 30–Jul 7 |
| 7a & 7b | Not usually | Mar 27–Apr 3 | Jun 15–Jun 22 |
| 8a & 8b | Not usually | Mar 11–Mar 18 | May 30–Jun 6 |
Bloom dates are about 80 days after the sow or plant-out date.
Good companions
No well-established companions for lupine.
Where to buy lupine seeds
Botanical Interests · Burpee (each supplier's lupine seeds)
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See it growing
Search YouTube for "growing lupine" 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 Lupine in USDA zone 5b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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