Horseradish: Plant Roots Directly in the Garden Vegetable
How to Plant
- Roots received before you are able to plant may be stored in slightly moist soil or sand or wrapped in a damp cloth held in a cool cellar for a couple of weeks. Examine the roots frequently as they should not be allowed to dry out, not should they be allowed to decay from too much moisture.
- Plant horseradish in early spring as soon as the soil can be worked.
- Choose a location in full sun with moist, fertile and medium heavy. Horseradish is a perennial crop, so choose a planting site where the roots may spread undisturbed.
- Prepare the bed by turning the soil under to a depth of 8 inches. Level with a rake to remove clumps of grass and stones.
- Set plants 18 inches apart in rows 30 inches apart. Plant with the thick or larger end up, either in an upright or horizontal position. When planting in a vertical position, a stick or dibble 1 inch in diameter may be used to make the hole in which to plant the root. Cover the roots with 3 inches of soil.
- Plants may take 4-6 weeks to emerge.
How to Grow
- Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, so control them by either cultivating often or use a mulch to prevent their seeds from germinating. Avoid disturbing the soil around the plants when weeding.
- Keep plants well watered during dry periods to promote rapid, uninterrupted growth. Plants need about 1 inch of rain per week during the growing season. Use a rain gauge to check to see if you need to add water. It’s best to water with a drip or trickle system that delivers water at low pressure at the soil level. If you water with overhead sprinklers, water early in the day so the foliage has time to dry off before evening, to minimize disease problems. Keep the soil moist but not saturated.
- Several sprouts will grow from each root. The weaker sprouts should be broken off so that one or two of the strongest remain.
- When the largest leaves reach 10 inches long, dig up main root and remove side roots on top (but NOT the bottom). Remove nearly all the leaves on the crown, then replant crown.
- Repeat after 6 weeks.
- Monitor for pests and diseases. Check with your local Cooperative Extension Service for pest controls recommended for your area.
- Many gardeners make new plantings within five years as older roots tend to become woody.
Harvest and Preserving Tips
- Dig up roots after fall frost kills the foliage.
- Store in refrigerator in an airtight plastic bag.
- Use grated roots as a condiment.
- Leaves may be used in salads.
- Horseradish may be dried, either sliced or grated. It may be frozen using a vacuum sealer to help retain the savory oils.
- Horseradish may be stored whole in a box of dry sand in a cool, dark place through the winter and used as needed. Or preserved in vinegar.
Common Disease Problems
Bacterial Leaf Spot: First signs are small translucent spots with a broad yellowish edge that slowly enlarge and become angular or irregularly circular with a reddish center. It thrives in cooler temperatures. Burpee Recommends: Remove infected plants and do not plant horseradish in the same area. Avoid overhead watering. Do not work around plants when they are wet.
Cercospora Leaf Blight: Small flecks which develop a yellowish halo appear on the leaves and turn brown and coalesce. They cause the leaves to wither and die. Burpee Recommends: Remove infected plants and destroy all plant debris.
Root Rots: A number of pathogens cause root rots. Burpee Recommends: Practice crop rotation and do not plant related crops in the same area for several years. Pull up and discard infected plants. Make sure your soil has excellent drainage. Contact your Cooperative Extension Service for recommendations.
Rust: A number of fungus diseases that cause rust colored spots on foliage, stalks and husks. Burpee Recommends: Plant resistant varieties. Practice crop rotation. Remove infected plants.
Turnip Mosaic Virus: This causes ring spots and mosaic or mottling on the leaves and black streaks on the leaf stalk. Burpee Recommends: Remove infected plants and discard.
Common Pest and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps which feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Cabbage Looper: These worms are green with a white stripe on either side, about 1-1.5 inches long. Burpee Recommends: Hand pick. Floating row covers can help prevent their laying eggs on the plants.
Flea Beetles: These small hopping beetles feed on plant foliage and may spread diseases. Burpee Recommends: Rotate crops with plants in a different plant family. Use floating row covers to prevent damage to young foliage.
Leafhoppers: Leafhoppers cause injury to leaves and stunt growth. They also spread disease. Burpee Recommends: Remove plant debris. Use insecticidal soaps. Consult your Cooperative Extension Service for other insecticide recommendations.
Slugs: These pests leave large holes in the foliage or eat leaves entirely. They leave a slime trail, feed at night and are mostly a problem in damp weather. Burpee Recommends: Hand pick, at night if possible. You can try attracting the slugs to traps either using cornmeal or beer. For a beer trap, dig a hole in the ground and place a large cup or bowl into the hole; use something that has steep sides so that the slugs can’t crawl back out when they’re finished. Fill the bowl about ¾ of the way full with beer, and let it sit overnight. In the morning, the bowl should be full of drowned slugs that can be dumped out for the birds to eat. For a cornmeal trap, put a tablespoon or two of cornmeal in a jar and put it on its side near the plants. Slugs are attracted to the scent but they cannot digest it and it will kill them. You can also try placing a barrier around your plants of diatomaceous earth or even coffee grounds. They cannot crawl over these.
Horseradish FAQs
My roots arrived with a mold on them, will they be OK to plant? Yes, this is most likely a surface mold that will not affect the plants. It comes from the roots being in transit several days in warm conditions without adequate air circulation. If the roots are not mushy or do not have a foul odor, wash off the mold and plant.
Can I grow horseradish in zone 10? No, horseradish is only recommended to zone 9 because the plants require cool falls and winters for the best flavor.
How long before I can harvest my horseradish? Do not harvest horseradish the first year as this will weaken the plants. Wait until the end of the second year after planting to harvest.
How do I get the hottest horseradish? For the hottest horseradish, use the roots as soon as possible after harvest, the heat fades the longer the roots are stored. Roots should be creamy white when cut. The pungency also begins to wane when fresh crushed horseradish is exposed to air. When making your own sauce, add vinegar to stabilize the flavor about three minutes after grating. Add 2-3 tablespoons of white distilled vinegar and ½ teaspoon of salt to each cup of grated root.
Are the leaves edible? Yes, the fresh leaves may be used in salads.