Horseradish is an ancient herb and a member of the mustard family. The plant’s leaves are edible and make a tangy addition to fresh salads; however, the plant is typically grown for its tasty roots. This perennial herb looks harmless enough as a root, but cut it open and that’s when it lets its powerful spicy aroma be known.
How to Grow Horseradish
Horseradish is a beautiful leafy plant with a thick, fleshy taproot system. The taproot is the important part of the plant because as it grows, it sends out a good number of fleshy lateral roots in the top 12 inches of the soil. The main root can also divide itself to grow more large roots.
The plants also feature large spiky leaves and long stems of white flowers. Flowers appear in mid-summer, but the roots stay in the ground until fall. Gardeners who grow horseradish grate the roots to use with vinegar as a simple condiment or to mix into flavorful sauces. Wasabi is a type of Japanese horseradish that’s commonly served with sushi.
- Horseradish is an easy to grow perennial plant that’s planted in early spring. Locate a permanent planting place that gets full sun. When the garden soil is dry enough to be worked, dig deeply and add in plenty of compost to create a fertile, well-draining soil. Avoid amending the soil with too much nitrogen to keep plants a manageable size.
- For ease of planting, buy healthy horseradish root cuttings or transplants at the Garden Center. Look for the straightest roots you can find that are 9 to 10 inches long (with the diameter of a nickel) or look for horseradish transplants.
- Wait for soil temperatures to warm to 60 degrees before planting. If you’re planting horseradish root cuttings, plant them so the upper end of the horseradish cutting is 2-5 inches below the surface of the soil and at an angle, instead of straight up and down.
- Pack the soil firmly around the cutting to help give the roots a good start. Place root cuttings 18 to 20 inches apart so plants have plenty of room to grow. Water in and keep the soil moist.
- If planting transplants, dig a hole that’s twice as deep as the roots are long. Place the plant in the hole and refill with soil, keeping the base of the leaves at soil level. To prevent transplant shock and wilted leaves, water in and provides shade for several days.
- Keep the soil moist and eliminate weeds that can compete with the plant for water and nutrients by mulching with an organic mulch (like straw).
- Once established, horseradish has moderate water needs so water about once a week. If the soil is allowed to dry out, the roots can become stunted or grow in odd shapes instead of the long, straight roots that are best to use in cooking.
- If you amended the soil with enough compost at the beginning of the season, the plants may not need additional fertilizer. If you do need to fertilize, use an organic fertilizer (5-10-10).
- Horseradish grows best in the coolest months, so the roots are typically dug up in the late fall after the leaves wilt from frost. Brush soil away at the base of the plant and place a garden fork or spade near the roots to lift carefully. Try to keep from breaking any of the roots.
- After the first killing frost, some gardeners dig a few roots at a time, allowing the rest to stay in the soil. Other gardeners dig up the roots, remove the leaves, prepare some horseradish and replant the upper portion of the root, to start on next year’s crop.
Plant horseradish with other perennial edibles:
Materials for Success
- Soil thermometer
- High-quality compost and manure
- Mulch (like straw or dry shredded leaves)
- Low-nitrogen organic fertilizer
- Soaker hose
- Garden (spading) fork or hand fork
To learn more about growing horseradish or about growing your own edible vegetable garden, contact the pros at Nick’s Garden Center.