When I was growing up, horseradish was something that lived in a jar in the nether regions of the refrigerator. It wasn't until a few decades later that I discovered horseradish as a garden plant—and the delights of using it fresh in the kitchen. Homegrown horseradish has a clear, fresh taste and packs more zing than the store-bought variety, and it must rank in the top five easiest-to-grow food plants, because it thrives in almost any condition. Don't wait as long as I did to grow horseradish in your garden!
Horseradish is a rugged, cold-hardy (to USDA Plant Hardiness Zone 3) perennial that grows best where there's enough of a winter to force the plants into dormancy. You can choose from two widely available types of horseradish: common horseradish, which has broad, crinkled leaves, and Bohemian, which has narrower, smooth leaves and better disease resistance, though disease is very rarely a problem for home gardeners.
Choosing a site. Horseradish thrives in full sun but tolerates light shade. As for soil, horseradish can take almost anything but consistently waterlogged conditions. Site your horseradish in an out-of-the way spot, because you won't want to move this perennial once it is planted.
Planting. Grow horseradish from plants or root cuttings set out in spring or fall. You won't be able to find seeds, but roots are often available at farmers' markets, supermarkets, and retail and mail-order nurseries. Cut off the top third to half of the root to use in the kitchen, saving the bottom part to plant. Loosen the soil to 12 inches deep and add a shovelful of compost. Plant the root cutting at a 45-degree angle, with the top of the cutting 2 inches below the soil line. Be sure not to plant the cutting upside down. Root cuttings from nurseries generally come precut and just need to be planted. One plant is usually plenty for a family. If you love horseradish so much that you need more than one plant, space them 30 inches apart.
Growing. Horseradish needs little or no attention in order to thrive. To keep the plant from looking ratty, however, water it once a week during dry spells and use a couple of inches of mulch around the plant to help conserve moisture.
Harvesting. You can enjoy your first horseradish harvest one year after planting. Carefully dig away the soil from around the main root, taking care to free up the side roots and remove them at the same time. For the best yields, Oregon State University recommends harvesting after frost kills the foliage. Scrub the main root under running water and dry well. If enclosed in a perforated plastic bag, horseradish root will keep in the vegetable bin of your refrigerator for three months or even longer.
The most common issue gardeners face with horseradish is not how to grow it but how to keep it from growing where they don't want it. To control its spread, remove the entire root, including its branches, when harvesting; then replant only the number of roots you desire as plants for the following season. Whatever you do, don't till up ground containing horseradish root or place roots in your compost pile, because you risk spreading the plant all over the garden.
Photo: Rob Cardillo