Growing Horseradish

Horseradish is a tough, cold-hardy perennial that grows best where there is enough of a winter to force the plants into dormancy. There are two types of horseradish: common, which has broad, crinkled leaves, and Bohemian, which has narrower, smooth leaves.

Choosing a Site

Horseradish thrives in full sun but tolerates light shade. It grows best in deep, rich, moist loamy soil. Roots tend to be malformed and yields are reduced if grown in hard, shallow, or stony soils.

Planting

Set out your plants or root cuttings in early spring, as soon as the soil is workable, or fall. Roots are available at farmer's markets, supermarkets, and mail-order nurseries. You can use the top half of the root to make a peppery condiment and plant the bottom half. Loosen the soil to 12 inches deep and add a shovel full of compost. Plant the root cutting at a 45-degree angle, with the top of the cutting 2 inches below the soil line. For smoother, straighter, and fatter roots, remove the suckers — leaf-bearing sprouts that form above ground. When the plants are about 8 inches tall, use a sharp knife to cut off the suckers, leaving only three or four at the center of the crown. One plant is usually plenty for a family.  If you do plant more than one root, space them 30 inches apart.

Growing

Horseradish needs little to no attention in order to thrive. To keep the plant from looking too unsightly, water once a week during dry spells and use a couple inches of mulch around the plant to hold in moisture. Compost should give the plant most of its food for the season, but if needed apply a balanced or low-nitrogen fertilizer two to three times during a growing season. The soil should be pH 5.5 to 5.7. You can check your soil pH with a soil test. Soil test kits are available at your local Penn State Extension office.) Also, keep your bed clear of weeds.

Harvesting

 You can start using the horseradish one year after planting. Use a garden fork or shovel. Carefully dig away the soil from around the main root, being careful to free up the side roots and remove them at the same time. Start harvesting after frost kills the foliage. Scrub the main root under running water and dry well. You can store the roots in a perforated plastic bag in the vegetable bin of your refrigerator for three months or longer. Prepare your horseradish in a well-ventilated area or even outside. It emits fumes that can make your nose run and irritate your eyes. Grating horseradish crushes the cells of the root, releasing the volatile oils which give horseradish its heat. Adding vinegar stops the enzymatic reaction. The longer you wait to add the vinegar, the hotter your horseradish will be. For instructions on preparing and preserving fresh horseradish, consult a cookbook or recipe site online.

Problems

The most common problem with horseradish is how to keep it from growing where you don't want it. It can become aggressive if not kept under control. To control the spread, remove the entire root, even the branches, when harvesting. Replant only the number of roots you want for the following season. Whatever you do, don't till up soil containing horseradish roots because you will risk spreading the plant all over the garden. Almost every little piece of root will sprout where it lies.

Horseradish flea beetle is a serious pest on foliage. It deposits egg clusters on leaf petioles (leafstalk). Its larvae burrow into the petioles and will kill some of the leaves. A floating row cover will help. Horticulture oils also have some repellent effect on this insect. Remember to read and follow the directions on all insecticides.