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Horseradish: How to Plant, Grow, and Harvest Horseradish | The Old Farmer's Almanac

Horseradish

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Kuttelvaserova Stuchelova/Shutterstock
Botanical Name
Armoracia rusticana
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How to Plant, Grow, and Harvest Horseradish

Margaret Boyles
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If you want to plant horseradish, spring is the season—but only in places where winters freeze hard. Here’s how to plant, grow, and harvest horseradish in your garden.

About Horseradish

An exceptionally hardy perennial, horseradish belongs to the venerable plant family Cruciferae (“cross-bearing,” for the tiny, cross-shape flowers characteristic of all members of this family), which includes cabbage, broccoli, cauliflower, brussels sprouts, among other commonly-grown vegetables.

Horseradish sends up coarse, elongated, emerald green leaves that resemble those of common curly dock. This foliage, which rarely grows more than 2 feet tall, belies the real action underground: In rich soil, the fleshy horseradish taproot can penetrate as deep as 10 feet if left undisturbed for several years and will send out a tangled mass of horizontal secondary roots and rootlets over a diameter of several feet.

If severed from the main taproot, any rootlet can give rise to a new plant; this is one way to start a crop. Aspiring horseradish growers can also obtain root cuttings—sometimes called “starts” or “sets”—from seed companies and from many local garden supply stores.

Planting

Horseradish is adaptable and tough, but providing it with the proper growing conditions will produce the biggest, sweetest, and most flavorful roots.

  • Plant in a location that gets full sun. Horseradish will tolerate partial sun, but yields will not be as good.
  • Plant in moist, fertile, loamy soil with slightly-acidic to neutral pH. Prepare the soil by tilling 8 to 10 inches down and clearing out any roots or rocks that could impede the horseradish’s growth.
  • Plant it well away from other garden crops, or follow the practice of savvy gardeners and plant the roots in buried lengths of drainage tile or even a bottomless 5-gallon bucket, to check their spread.

When to Plant Horseradish

  • Plant horseradish sets—small pieces of horseradish root—in early spring, as soon as the soil can be worked.
  • Horseradish requires a long growing season, so plan to harvest in the fall (just before a freeze) or in early spring of the following year.

How to Plant Horseradish

Plant horseradish by laying sets or pieces of roots about 18 inches apart and at a 45° angle, in a trench 3 to 4 inches deep. Sets generally come with the lower end sliced off on the diagonal to indicate which end should slant down. With fully horizontal planting, leaves will sprout forth from several points along the length of the set, which is less ideal. Cover over with topsoil after planting. 

Growing
  • Fertilize established horseradish in the early spring (the plants make vigorous top growth all summer and then begin storing starch in the root in the fall, which fattens them).
  • Water and weed regularly, but weed carefully when plants are still young.
  • Protect the crops against those pests that commonly attack cabbage family members, like cabbageworms and flea beetles.
  • To prevent the rampant spread of the roots and a buildup of disease organisms, harvest the roots regularly—ideally, every spring or fall—and rotate the bed to a new place every so often, setting pencil­-size sets broken off the main roots. 
Harvesting
  • Gardeners disagree as to whether spring-dug or late-fall–dug horseradish gives the finest flavor, but most agree that roots dug in summer are unpalatable.
  • We tend to dig our main supply of roots in late October or early November, after the foliage is killed by frost and just before the ground freezes.
  • Use a garden fork or shovel and carefully dig up the roots.

How to Store Horseradish

  • To prepare for storage, trim foliage down to about 1 inch and clean the roots under running water, scrubbing off any dirt. Allow roots to dry before storing.
  • Store horseradish in damp sand in the root cellar, in a dark area. Temperatures shouldn’t drop below freezing.
  • For more immediate use, a small supply of roots will keep well in a perforated plastic bag in the refrigerator for up to a couple months.

Two caveats govern both culinary uses of horseradish:

  • Keep the roots refrigerated to maintain flavor and nutritional value, grating them only as needed, and use them raw.
  • When adding horseradish to hot foods, such as rarebits, sauces, or fondues, stir it in just before serving. 
Wit and Wisdom
  • July is National Horseradish Month!

How Horseradish Gets Its Bite

Horseradish gets its characteristic bite from the interaction of two compounds, isolated from each other in separate cells of the plant. Intact roots and leaves have no horseradish-y smell but must be bruised, chopped, shredded, or chewed to bring the two compounds together. The finer the grating or grinding, the more pungent and richly flavored the root becomes.

Horseradish Health Benefits

Horseradish roots pack a nutritional wallop that few cultivated plants, and certainly no other root crop, can match. The freshly grated root contains more vitamin C than most common fruit, including oranges. The root is rich in calcium, iron, thiamine, potassium, magnesium, trace minerals, and proteins, yet desirably low in phosphorus and sodium. Horseradish is 20 times richer in calcium than the potato (with skin) and contains nearly four times the vitamin C and three times the iron.

There are those who warn that overconsumption of horseradish root will irritate the sensitive lining of the digestive tract; they suggest limiting use to a quarter teaspoon at a time. To them, we offer the remark of a Yankee octogenarian who has grown, processed, and eaten horseradish all of his adult life and takes his daily dose of homemade horseradish sauce straight, by the tablespoonful, accompanied by much lip-smacking, tearing, sniffling, and sweating. “Oh, that’s good stuff,” he exclaims. “Question in my mind is not how I’d get hurt from eatin’ it, but how much worse off I’d be without it.”

Pests/Diseases

Horseradish Pests and Diseases

Pest/Disease Type Symptoms Control/Prevention
Aphids Insect Misshapen/yellow leaves; distorted flowers; leaf drop; sticky “honeydew” (excretion) on leaves; sooty, black mold Knock off with water spray; apply insecticidal
soap; inspect new plants carefully; use slow- release fertilizers; avoid excess nitrogen; encourage lacewings, lady beetles/bugs, spiders
Cabbageworms Insect Leaves have large, ragged holes or are skeletonized; heads bored; dark green excrement; yellowish eggs laid singly on leaf undersides Handpick; use row covers; add native plants to invite beneficial insects; grow companion plants (especially thyme); spray Bacillus thuringiensis (Bt)
Cutworms Insect Wilting; severed stems of young plants just above or below soil line Handpick; in spring before planting, cultivate soil to reduce larvae; wrap a 4-inch-wide collar made from cardboard or newspaper around each stem, sinking 2 inches into soil; weed; use row covers; destroy crop residue
Flea beetles Insect Numerous tiny holes in leaves Use row covers; mulch heavily; add native plants to invite beneficial insects
Wireworms Insect Young plants severed; stunting/wilting; roots eaten; roots bored Trap by digging 2- to 4-inch-deep holes every 3 to 10 feet, fill with mix of germinating beans/corn/peas or potato sections as bait, cover with soil or a board, in 1 week uncover and kill collected wireworms; sow seeds in warm soil for quick germination; provide good drainage; remove plant debris; rotate crops
Cooking Notes

Preparing Horseradish for Use as a Condiment

Peel the root and finely grate it, or cut it into cubes and place the horseradish cubes into a blender. Add one or two ice cubes and grind the horseradish until smooth. (Make sure that you do this in a well-ventilated room and use eye and nose protection. The smell will be quite pungent.)

For mild horseradish, add 1 to 2 tablespoons of white vinegar and a few pinches of salt immediately. For hot and spicy horseradish, wait 3 minutes before adding 1 to 2 tablespoons of white vinegar and a few pinches of salt.

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