Horseradish is a perennial vegetable/herb grown for its pungently hot roots, which are used to spice up many dishes from roast beef to cocktail sauce. They are grown from root divisions and can be extremely aggressive.
Description: Horseradish is a clump forming plant, in the Brassicaceae family. Small, white flowers are produced on long stalks. You can clearly see the resemblance to other Brassicas, like cabbage and broccoli.
Days to Harvest: Spring planted horseradish roots will be ready to harvest in Oct/Nov, 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. 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.
Exposure: Full Sun to Partial Shade.
Soil: Horseradish likes a slightly acidic to neutral soil. A loose soil, rich in organic matter will produce the best roots.
Planting: You basically have 3 choices for growing your horseradish:
• Grow it in the ground as a perennial and allow it to spread.
• Grow it in a container, where you can control it.
• 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 with plenty of organic matter. Dig 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, 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. Feed or side dress plants every 3–4 weeks.
Growing Horseradish in a Container — You’ll need a sizable container, we recommend a container that it is at least 15 gallons. 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, 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.