Primula in Zone 4a & 4b
Primula vulgaris
Yes, primula grows in zones 4a and 4b and comes back each year. Start seeds indoors Mar 6–Mar 13 and plant out May 1–May 8.
When to plant primula in zone 4b
Zones 4a and 4b share the same average frost dates, so this page covers both.
Method: Start indoors: Start indoors from seed, then transplant outside. It needs a head start most zones can't give it by direct-sowing alone.
| Start indoors | Mar 6–Mar 13 |
|---|---|
| Direct sow / transplant outside | May 1–May 8 |
| Estimated bloom | First real harvest the season after planting |
Spacing: 2 per square foot (square-foot-gardening spacing). Mature height: 0.5-1 ft.
Before you plant: Primula has a winter-hardiness note for zone 4b. See the details below.
Plant alongside it in zone 4b
These go outside within two weeks of primula in zone 4b, so one planting day can cover them.
- Agrostemma (Corn Cockle)May 1–May 8
- AstilbeMay 1–May 8
- Bachelor's Button (Cornflower)May 1–May 8
- Basket-of-GoldMay 1–May 8
- Bupleurum (Thoroughwax)May 1–May 8
- CalendulaMay 1–May 8
Primula is one of the earliest things in the garden, often flowering before the last frost has passed.
How primula fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Primula takes about 1 growing season to reach full flowering, so what matters here is how many of these seasons it gets, not whether one is long enough.
Primula is hardy in zones 4-8, so in zone 4b it stays in the ground through winter and comes back rather than being replanted. Allow about 0.75 ft of spread at maturity.
Primula planting windows in every zone
Zone 4b 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 (your zone) | Mar 6–Mar 13 | May 1–May 8 | First real harvest the season after planting |
| 5a & 5b | Mar 1–Mar 8 | Apr 26–May 3 | First real harvest the season after planting |
| 6a & 6b | Feb 14–Feb 21 | Apr 11–Apr 18 | First real harvest the season after planting |
| 7a & 7b | Jan 30–Feb 6 | Mar 27–Apr 3 | First real harvest the season after planting |
| 8a & 8b | Jan 14–Jan 21 | Mar 11–Mar 18 | First real harvest the season after planting |
Good companions
No well-established companions for primula.
Where to buy primula seeds
True Leaf Market (each supplier's primula seeds)
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing primula" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 4b calendar · Plan your beds in the Garden Designer →
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Growing Primula in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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