How to grow horseradish

Armoracia rusticana · Brassicaceae · Vegetable

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

When to plant horseradish

Companions

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.

Figures are typical home-garden ranges from Cooperative Extension planting guides, cross-checked against multiple state sources. Your variety and conditions will vary.