Horseradish in Zone 4a & 4b
Armoracia rusticana
When to plant horseradish 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. Horseradish doesn't transplant well, or doesn't need the extra time indoors.
| Start indoors | Not typically started indoors |
|---|---|
| Direct sow / transplant outside | May 22–May 29 |
| Estimated harvest | Nov 18–Nov 25 (~180 days after direct-sowing) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 2-3 ft.
Horseradish is a perennial root crop grown from root cuttings rather than seed, and once planted, it tends to stay planted; any small piece of root left in the ground resprouts, which is both the plant's appeal and the reason gardeners give it a spot it won't outgrow its welcome in.
How horseradish fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Horseradish needs about 180 days from sowing to first harvest.
Good companions
No standout companions recorded yet for Horseradish.
Where to buy horseradish seeds
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing horseradish" 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 Horseradish in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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