Castor Bean in Zone 3a & 3b
Ricinus communis
When to plant castor bean in zone 3b
Zones 3a and 3b share the same average frost dates in our data, so this page covers both.
Method: Direct sow: Direct-sow outside. Castor Bean doesn't transplant well, or doesn't need the extra time indoors.
| Start indoors | Not typically started indoors |
|---|---|
| Direct sow / transplant outside | Jun 6–Jun 13 |
| Estimated bloom | Sep 14–Sep 21 (~100 days after direct-sowing) |
Spacing: about 10 square feet per plant (square-foot-gardening spacing). Mature height: 6-10 ft.
Castor bean is included here so this site can state plainly what it is, rather than leaving a gardener to find out from a packet that does not say.
How castor bean fits zone 3's season
Zone 3b's frost-free window runs about 98 days, from May 30 to September 5. Castor Bean needs about 100 days from sowing to first harvest.
Good companions
No standout companions recorded yet for Castor Bean.
Where to buy castor bean seeds
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing castor bean" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 3b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →
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Growing Castor Bean in USDA zone 3b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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