Horseradish Growing Guide
Horseradish (Armoracia rusticana) is a perennial root herb that is easily grown in USDA zones 3 to 7. It needs a cold enough winter to go into dormancy. The leaves die back with the first frost. The leaves are not used, it is the root that is harvested and used.
Many people first think of it as the tang in a Bloody Mary. Its many other uses are for adding flavor and heat to sauces and gravy served with beets, beef, chicken and shrimp. Horseradish is also a good source of Vitamin C and was used in the past as a cure for scurvy.
It is a perennial member of the cruciferous family which includes broccoli, Brussels sprouts, cabbage, cauliflower, collards, kale, and kohlrabi. It is cultivated for its large white tapered root that is grated. The grated root is often mixed with vinegar for the hottest horseradish sauce.
Plan Before You Plant
Horseradish is a perennial herb and will be in the location you choose for a long time. You may want to set aside a nice sunny area of your garden for some perennials such as blueberries, rhubarb and horseradish because they prefer a slightly acid soil and make good companion plants. It is considered deer resistant.
Soil Preparation
The soil should be nice loose well drained organic garden soil with the soil pH between 5.0 to 7.0. As soon as the soil is frost-free and can be worked, till the soil by digging down 8 to 12-inches turning the soil over with a garden fork. Remove any large rocks and stones. The small stones remaining will do no harm and actually benefit the soil by adding some micronutrients to the soil.
Planting
Horseradish does best in full sun but can tolerate part sun. The best time to plant horseradish is in the spring a few weeks before the last frost date. Horseradish is not started from seed. The roots or crowns can be obtained from online or mail order sources as well as a farmers’ market, grocery store, Asian market or another gardener.
If you have a root crown with a growth bud showing, plant it with the crown even with the surrounding soil. Root cuttings 6 to 8-inches long should be planted with the top of the cutting 2-inches below the soil surface, making sure that root cutting is not planted upside down. Keep the soil moist by watering daily as the horseradish grows new roots, backing off as the plant grows.
The leaves grow 3 to 4-feet high and will not need much attention other than keeping out competing weeds.
One plant is usually enough for one family. If more is planted space them 18 to 24-inches apart.
Watering and Care
When the leaves are a few inches tall add a nice loose mulch of shredded leaves or pine straw to shade the plant roots. This will keep the weeds out, the soil cooler and help retain moisture. Keep the mulch a couple of inches away from the stem. During dry spells give some water each week.
Harvesting Horseradish
The roots are usually harvested by carefully digging up the root in the fall after the first frost kills the leaves. The entire root can be dug up or just the side roots. The roots that are left in the ground will keep on growing for next year.
It can be found in the grocery store prepared in vinegar, but the taste is not the same as a freshly grated root. After digging up the root scrub it under running water. Peel it like you would do a carrot. If you are sensitive to the fumes, do it outside or under water, like an onion.
Pieces of the root can be frozen and stored for later use. For small amounts you can use a box grater. If you are adding grated horseradish to a pot roast gravy, a small amount will add an interesting flavor. If you like it hotter you can add more of the grated root.
Larger amounts can be grated in a blender or a food processor. After cleaning and peeling the root, cut it up into 1/2-inch pieces. Put the pieces into a blender or food processor with a small amount of water and a couple of ice cubes. Again if you are sensitive to the fumes do it outside. Immediately after grating the root, drain off some of the excess liquid and put it into a glass jar. Add some white wine vinegar to preserve the flavor.
After 2 to 3-years the main root will tend to get woody. At this time you can harvest the main root and the larger offshoots of the main root should be divided and replanted for a new crop.
Diseases and Pests
Horseradish is generally pest free; in some areas cabbage worms (Pieris rapae) are found. The cabbage worm is green with yellow strips and the adult is the familiar white butterfly with black spots on the forewing. The caterpillars chew holes in the leaves and if you see a large number of holes inspect the leaves looking on the underside and hand picking any you find.
White rust and bacterial leaf spot are sometimes problems that affect the leaves. Prevention is the best way to control any problems by removing any infected plant leaves and toss them into the garbage, not the compost pile.
Popular Horseradish Varieties
Common or Maliner Kren, Bohemian, Big Top, Variegata.
Sources: Seeds Now, Gurney's Seed and Nursery, Park Seed
Tips and Warnings
Horseradish can spread by underground roots. Those new shoots can be removed and used. If you want to remove the entire root system you will need to carefully dig it up. Remove any root fragments you find. Do not use a tiller because the root fragments will grow into new plants and will be even more difficult to remove.
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