How to grow horseradish
Armoracia rusticana · Brassicaceae · Vegetable
When to plant horseradish: the short answer
Sow outdoors about 3 weeks before the last frost; for a fall crop, sow about 4 weeks before your first fall frost. Seeds germinate in soil from 45 to 75°F, fastest near 60°F.
Zone 5: plant out Apr 2 – Apr 19. Zone 7: plant out Mar 8 – Mar 25. Zone 9: plant out Jan 23 – Feb 9. See every zone.
Horseradish is a cool-season vegetable in the Brassicaceae family, almost always sown straight into the ground where it will grow. It wants full sun (six or more hours of direct light) and steady, even moisture. From sowing to first pick is about 150–180 days. It is one of the toughest crops here, standing through hard frost and often improving for it.
Grower’s note: Extremely vigorous and nearly impossible to remove once established - grow it in a sunken tub or a bed of its own. Plant a pencil-thick root cutting at a 45-degree angle in spring, dig the whole root after fall frost, and replant a side root for next year.
Sowing
Sow about 4″ deep, into soil between 45–75°F — germination is quickest near 60°F. It is slow and often erratic to germinate (21–42 days). It does not transplant well, so sow it in its final position rather than starting it in pots.
Spacing & layout
Give each plant about 18″ along the row with roughly 30″ between rows. On a square-foot grid that is one plant per 4 square feet. Allow at least 24″ of loose, workable soil for the roots. It grows well in containers at least 24″ deep.
Fitting it to your season
Horseradish is a perennial: you plant it once and it comes back and crops for years, so it does not fit the annual sow-and-harvest cycle. Give it a permanent, well-prepared spot out of the way of yearly digging. It takes one to three seasons to reach a full harvest — take little or nothing the first year while the plant establishes.
Quick facts
Growth stages: how long horseradish takes to grow
From sowing to first harvest takes roughly 150-180 days (21-26 weeks), with seedlings appearing after 21-42 days in soil around 60°F. It is a perennial, so once established it comes back and crops year after year.
When to plant horseradish
When to plant horseradish by USDA zone
Dates worked out from each zone’s typical frost dates for 2026. Find your zone on the zone map, or pick your state below for dates from its own frost dates. Zones 11 and above are frost-free, so timing there depends on heat and rain instead.
| Zone | Last / first frost | Start indoors | Sow or plant out |
|---|---|---|---|
| Zone 3 | May 15 / Sep 15 | - | Apr 17 – May 4 |
| Zone 4 | May 10 / Sep 25 | - | Apr 12 – Apr 29 |
| Zone 5 | Apr 30 / Oct 5 | - | Apr 2 – Apr 19 |
| Zone 6 | Apr 15 / Oct 15 | - | Mar 18 – Apr 4 |
| Zone 7 | Apr 5 / Oct 25 | - | Mar 8 – Mar 25 |
| Zone 8 | Mar 20 / Nov 5 | - | Feb 20 – Mar 9 |
| Zone 9 | Feb 20 / Nov 30 | - | Jan 23 – Feb 9 |
| Zone 10 | Jan 30 / Dec 15 | - | Jan 2 – Jan 19 |
Companions
Potato
No strong antagonists recorded.
Common problems
Pests: flea beetle, aphids.
Diseases & disorders: white rust, cercospora leaf spot.
Same family (Brassicaceae)
Rotate these so they don’t follow each other in the same bed year to year.
Questions gardeners ask
When should I plant horseradish?
Sow outdoors about 3 weeks before the last frost; for a fall crop, sow about 4 weeks before your first fall frost. Seeds germinate in soil from 45 to 75°F. The table on this page gives dates for each USDA zone, and the planting calendar gives dates for your own state or ZIP code.
How long does horseradish take to grow?
About 150-180 days from sowing to the first harvest. Seeds germinate in 21-42 days, fastest in soil around 60°F.
How much sun does horseradish need?
It needs at least six to eight hours of direct sun a day.
What soil pH does horseradish need?
A soil pH between 6.0 and 7.0. Test before adding lime or sulfur - see the soil pH and testing guide.
How far apart should I plant horseradish?
Space plants about 18 inches apart in rows 30 inches apart, or one plant per 4 square feet in a square-foot bed. Sow seeds about 4 inches deep.
Can I grow horseradish in a container?
Yes. Use a container at least 24 inches deep with drainage holes and a good potting mix, and water more often than you would in the ground.
Figures are typical home-garden ranges from Cooperative Extension planting guides, cross-checked against multiple state sources. Your variety and conditions will vary.