Radish in Zone 4a & 4b
Raphanus sativus
When to plant radish in zone 4b
Zones 4a and 4b share the same average frost dates in our data, so this page covers both.
Method: Direct sow: Direct-sow outside. Radish doesn't transplant well, or doesn't need the extra time indoors.
| Start indoors | Not typically started indoors |
|---|---|
| Direct sow / transplant outside | Apr 17–Apr 24 |
| Estimated harvest | May 12–May 19 (~25 days after direct-sowing) |
Spacing: 16 per square foot (square-foot-gardening spacing). Mature height: 0.5-1 ft.
Radishes are the fastest crop you can grow in a home garden, 25 days from seed to harvest, direct-sown as early as four weeks before your last frost. They're also useful beyond the kitchen: radish is a documented trap crop that draws cucumber beetles away from more valuable plants.
How radish fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Radish needs about 25 days from sowing to first harvest.
Good companions
- Cucumber: Reputed as a trap crop that draws cucumber beetles away, but the documented trap-crop research for cucumber beetles points to Blue Hubbard squash specifically, not radish. Radish IS a real, documented trap crop, but for flea beetles on brassica crops — a different pest and crop pairing than this one. Treat this specific pairing as garden tradition, not measured evidence.
Where to buy radish seeds
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing radish" 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 Radish in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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