Calendula in Zone 4a & 4b
Calendula officinalis
When to plant calendula in zone 4b
Zones 4a and 4b share the same average frost dates in our data, so this page covers both.
Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Calendula tolerates either.
| Start indoors | Mar 27–Apr 3 |
|---|---|
| Direct sow / transplant outside | May 1–May 8 |
| Estimated bloom | Jun 20–Jun 27 (~50 days after planting) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 1-2 ft.
Calendula is one of the earliest things you can get in the ground. It tolerates a light frost and is often started before most of the garden is even planted, and it earns its keep once established, commonly reported to draw in the predatory insects that prey on tomato hornworms. What you get for the trouble is a low, 12- to 18-inch mound covered in simple daisy-like blooms in orange or yellow.
How calendula fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Calendula needs about 50 days from sowing to first harvest.
Good companions
- Tomato: Penn State Extension confirms calendula attracts beneficial insects that prey on aphids — the more specific claim that it targets hornworm predators isn't what that research actually shows, so treat calendula as a general aphid-predator draw near tomatoes rather than a hornworm-specific one.
Where to buy calendula seeds
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing calendula" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 4b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →
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Growing Calendula in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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