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 and are a required part of a Passover seder plate. The leaves can also be eaten, when young and tender, but should not be eaten by animals. There are many medicinal uses for horseradish.
|Botanical Name||Armoracia rusticana|
|Common Name||Horseradish, Red Cole, German Mustard|
|Plant Type||Perennial that can be grown as an annual|
|Mature Size||Height: 12 to 18 inches; width: 15 to 18 inches|
|Exposure||Full to partial sun|
|Soil Type||Loose, rich soil|
|Soil pH||Neutral (6.0 to 7.5)|
|Native Area||Central Europe|
How to Grow Horseradish
Horseradish (Armoracia rusticana) is a clump-forming perennial plant, in the Brassicaceae family. It 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.
There are three ways to plant your horseradish:
- Plant it in the ground as a perennial and allow it to spread.
- Plant it in a container, where you can control it.
- Grow it as an annual to get larger but fewer roots.
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 three to four weeks.
In general, horseradish is a forgiving plant that can handle a wide range of settings. Ideally, however, horseradish thrives in full sun or partial shade.
Temperature and Humidity
Horseradish likes cool weather. Its ideal daytime temperatures range from 45 to 75 degrees Fahrenheit.
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 the next growing season. If you are growing it in a pot or as an annual, lift it all.
Spring-planted horseradish roots will be ready to harvest in October or 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.
Horseradish plants are perennial in USDA hardiness zones three to nine. Since you will be harvesting the roots, however, this might not matter. If you want your horseradish to return the following year, you will need to leave some root in the ground or save it to plant next year. Saving it is often the preferred method because horseradish can become aggressive.
Varieties of Horseradish
Common horseradish may be the only variety you will find. There is also Armoracia rusticana 'Variegata,' which is more ornamental, with marbled leaves.
Pests and Problems
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.
Growing Horseradish as a Perennial
Horseradish has long taproots, so well-prepared soil is important. Prepare the garden bed by turning in a couple of inches of organic matter. A prepared bed is very 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 to 18 inches long. Horseradish will spread, so you won't need more than one or two plants to feed the whole family.
Dig holes about 6 to 8 inches deep and one foot apart. Plant one root per hole 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. Backfill the hole to cover the crown of the root with two to four inches of soil. Then water the plant well.
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-inch 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 large roots like the ones you purchase in a store, consider experimenting with growing horseradish as an annual, focusing on getting one large root, rather than many smaller roots. First-year roots tend to be the most pungent.
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 one large root, remove all but one or two of the shoots and allow them to grow larger.