Horseradish (Armoracia rusticana) is a hardy perennial grown for its pungent roots which are long and narrow, sometimes to two-feet long. Grow horseradish as an annual, in the second year the roots can become tough and fibrous. Horseradish is best grown in containers; it spreads readily and can easily grow out of control. Horseradish will be ready for harvest 140 to 160 days after planting.
Grow horseradish from crowns or root cuttings planted four to six weeks before the average date of the last frost for your area. Horseradish is a hardy perennial best grown as an annual. Keep horseradish from spreading in the garden by growing it in a container. Choose a container that will allow horseradish roots to grow 24 to 30 inches deep.
Plant horseradish in full sun although it will tolerate light shade. Grow horseradish in rich well-drained soil. Prepare the soil to a depth of 10 to 12 inches and remove stones and lumps that might cause the roots to split. Add sand and compost to the planting bed to keep the soil loose. Horseradish prefers a soil pH of 5.5 to 6.8. Horseradish is cold-hardy plant. Set out crowns or root cuttings 4 to 6 weeks before the average last frost date in your region. Horseradish grows best in cool, moist regions where the temperature stays between 45°F and 75°F.
Set crowns just at soil level. Plant roots in shallow trenches 3 to 4 inches deep and cover with 2 to 3 inches of soil. Slice root cuttings at a 30° angle or plant with the narrow end down; fill the trench until the wide end of the root is barely covered. Space roots 24 to 36 inches apart. Horseradish planted in the garden should be contained with wooden, metal, or masonry borders set at least 24 inches deep around the bed. Allow upright horseradish plants a full season to establish themselves in the garden. Potatoes, yams and sweet potatoes are good companion plants for horseradish.
To grow a large taproot use a spade to slice down around the plant 3 to 4 inches from the base pruning away side roots. Avoid leaving pieces of the root in the ground after harvest, they will produce new plants the following growing season.
Keep the soil evenly moist to prevent roots from drying and turning woody. Fertilize horseradish by adding organic compost, compost tea, or a very small amount of commercial 10-10-10 vegetable slow release fertilizer to the planting bed every month. Horseradish has no serious pest problems or serious disease problems.
Use a digging fork to loosen the soil on two sides of the plant, gathering up broken pieces of root as you dig. Then loosen the soil on the other side of the plant before attempting to pull it. Cut sections of root for use as needed after leaves are about 12 inches long (roots will then be 3 to 4 inches in diameter). Horseradish makes its best growth in late summer and fall, so delay harvesting until mid-autumn or later. Harvest all root before the ground freezes otherwise new plants will spring up the following year. Set aside or replant root pieces the size of a pencil, and store others in plastic bags in the refrigerator.
Grated horseradish can be kept in a glass jar in the refrigerator for one to two weeks. Whole roots can be packed in damp sawdust and kept for up to 10 months. To freeze horseradish, grate the roots and mix with vinegar and water.
Horseradish health benefits include essential vitamins and minerals like vitamin C, calcium, potassium and magnesium. The pungent root is high in dietary fiber, known to boost the immune system and has been linked to cancer prevention.
Horseradish Sauce Recipe
To prepare fresh horseradish for eating, peel a root and cut it into small pieces, then puree in a food processor with just enough water for chopping. Add a few pinches of salt and a teaspoon or two of white vinegar, and puree until only slightly lumpy. Place in a small clean jar, and add more vinegar if needed to cover the horseradish. Use within two weeks by mixing with mayo or sour cream to make horseradish sauce.