Horseradish in Zone 6a & 6b
Armoracia rusticana
Yes, horseradish grows in zones 6a and 6b. Plant it outside May 2–May 9.
When to plant horseradish in zone 6b
Zones 6a and 6b share the same average frost dates, so this page covers both.
Method: Direct sow: Direct-sow outside. It doesn't transplant well, or doesn't need the extra time indoors.
| Start indoors | Not typically started indoors |
|---|---|
| Direct sow / transplant outside | May 2–May 9 |
| Estimated harvest | Oct 29–Nov 5 (~180 days after direct-sowing) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 2-3 ft.
Plant alongside it in zone 6b
These go outside within two weeks of horseradish in zone 6b, so one planting day can cover them.
- TomatoMay 9–May 16
- Bush BeansMay 2–May 9
- Sweet CornMay 2–May 9
- CucumberMay 2–May 9
- ZucchiniMay 2–May 9
- Winter SquashMay 2–May 9
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 6's season
Zone 6b's frost-free window runs about 173 days, from April 25 to October 15. Horseradish needs about 180 days from sowing to first harvest.
Horseradish planting windows in every zone
Zone 6b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Harvest |
|---|---|---|---|
| 3a & 3b | Not usually | Jun 6–Jun 13 | Dec 3–Dec 10 |
| 4a & 4b | Not usually | May 22–May 29 | Nov 18–Nov 25 |
| 5a & 5b | Not usually | May 17–May 24 | Nov 13–Nov 20 |
| 6a & 6b (your zone) | Not usually | May 2–May 9 | Oct 29–Nov 5 |
| 7a & 7b | Not usually | Apr 17–Apr 24 | Oct 14–Oct 21 |
| 8a & 8b | Not usually | Apr 1–Apr 8 | Sep 28–Oct 5 |
| 9a & 9b | Not usually | Feb 22–Mar 1 | Aug 21–Aug 28 |
Harvest dates are about 180 days after the sow or plant-out date.
Good companions
- Potato: The most commonly repeated potato companion, credited with deterring the Colorado potato beetle. As with the claim that marigolds deter potato beetles, no extension or research source was found testing horseradish against this specific pest: treat it as garden tradition, not measured evidence.
Where to buy horseradish seeds
None of the seed suppliers we list carries horseradish seeds right now. A local garden center or a specialty seed house is the place to look.
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)
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Growing Horseradish in USDA zone 6b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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