Growing Horseradish in the Vegetable Garden

Horseradish is a perennial vegetable/herb grown for its pungent roots, which are used to spice up a variety of dishes from roast beef to cocktail sauce to a Passover Seder Plate. The leaves can also be eaten, when young and tender, but should not be eaten by animals. Horseradish is grown from root divisions and can be extremely aggressive. Many gardeners prefer to grow horseradish either in a container or within barriers placed in the soil.

Horseradish is a clump forming perennial plant, in the Brassicaceae family. It is grown predominately for its pungently hot roots. The leaves can also be eaten and there are many medicinal uses for horseradish.

Leaves: The dark green leaves are long, ovate and somewhat puckered and rough. They grow in a basel rosette.

Flowers: Small, white 4-petaled flowers are produced on long stalks. You can clearly see the resemblance to other Brassicas, like cabbage and broccoli.

Armoracia rusticana

Common Name:

Horseradish, Red Cole, German Mustard

Size:

Height: 12-18 in. (30-45 cm) Weight: 15-18 in. (38-45 cm)

Spring planted horseradish roots will be ready to harvest in October/November. In frost-free climates, winter harvest is recommended.

Harvest roots in the fall, ideally after the first frost. Dig around the base of the plant and lift the large, central root and as many of the smaller roots as possible. If you are growing your horseradish as a perennial, you can leave some in the ground and harvest as needed. Just keep in mind that the more broken pieces left in the ground, the more plants you will have. If you are growing it in a pot or as an annual, lift it all.

Common horseradish may be the only variety you will find. There is also Armoracia 'Variegata', which is more ornamental, with marbled leaves.

USDA Hardiness Zones 3--9.

Exposure:

Full sun to Partial Shade.

Few pests will bother the roots of horseradish, but there are several that will feed on the leaves, including: aphids, beet leafhopper, diamondback moth, flea beetles, and imported crucifer weevil. The aphids can be washed off. If the other pests become a nuisance, consider growing your horseradish undercover.

Soil: Horseradish likes a slightly acidic to neutral soil pH of about 6.0 to 7.5. A loose soil rich in organic matter will produce the best roots.

Planting: You basically have 3 choices for growing your horseradish:

1. Grow it in the ground as a perennial and allow it to spread.
2. Grow it in a container, where you can control it.
3. Grow it as an annual, to get larger, but fewer roots.

Growing Horseradish as a Perennial

Horseradish has long taproots, so a well prepared soil is important. Prepare the garden bed by turning in a couple of inches of organic matter. A prepared bed is extra important when growing plants as perennials, because you won't be able to correct your mistakes later.

Horseradish is grown from pieces of root that are about the diameter of a finger and 12–18 inches long. Horseradish will spread, so you won't need more than 1 or 2 plants for the whole family.

Dig a holes about 6–8 inches deep and 1 foot apart. Hold the root at a 45-degree angle with the crown, or large end, toward the top, at the soil line, and the small end at the base of the hole. Back fill the hole, covering the crown of the root with 2–4 inches of soil, and water well.

Horseradish is not a demanding plant, but you will get better quality roots if you keep the soil well watered, so the roots do not get woody, and feed or side dress your plants every 3–4 weeks.

Growing Horseradish in a Container

If you are worried about horseradish taking over your garden, growing it in a container may be the option for you. You'll need a sizable container, with at least a 30" depth for the roots to grow in. Plant the roots the same as if you were planting them in the ground. Container horseradish will need more frequent watering and monthly fertilizing.

Growing Horseradish as an Annual

To get the large roots like the ones you purchase in a store, you might want to experiment with growing horseradish as an annual, focusing on getting 1 large root, rather than many smaller roots. First year roots tend to be the most pungent.

You will still need to start with a bed prepared with lots of organic matter and plant the roots as directed above. As the plant starts to grow, it will send up multiple shoots. Each shoot is forming small roots and taking energy from the plant. To get 1 large root, remove all but one or two of the shoots and allow them to grow larger.

Sources:
University of Illinois Extension
University of Minnesota Extension