Horseradish (Armoracia rusticana) is a member of the Brassica family grown primarily for its root, which is ground into the popular condiment. The whole plant is edible though. The leaves are an early and nutritious green, sort of like kale, eaten raw when they are small and tender, and wilted or boiled when they grow larger. The vitamin C content of 100 grams of horseradish leaves can be 5 times the US RDA or more (as much as 3500mg/kg) and they contain a large amount of sinigrin, a compound with anticarcinogenic properties. The leaves are a little more bitter than Brussels sprouts, but have a similar flavor overall. Younger roots can also be cooked and eaten, although they get tough and fibrous as they mature. Although I like horseradish sauce, the amount that I use in a year would hardly justify growing a single plant. Instead, the greens are my main breeding interest with horseradish. There is great value in a perennial plant that can survive for 20 years or more and produce a crop of early greens each year. When your kale seeds are just thinking about germinating, horseradish greens can be ready to harvest. Added to that, horseradish is much more cold hardy than any of the various perennial kales and cabbages that can barely survive where winters dip below freezing.
These thongs are taken from a group of varieties grown from seed. While none of them are greatly different from any other horseradish that you have ever seen, they do flower more abundantly and set seed much more easily in my climate than the common horseradish does. They vary somewhat in plant size, leaf shape, and bitterness and spiciness of roots and leaves. These are varieties that I am evaluating and continuing to work with. If you want to try your hand at horseradish breeding, this would be a good place to start.
Horseradish “thongs” or “sets” are short sections of root. Ours are at least four inches long and 1/3 inch diameter. Whenever the soil is workable, plant them vertically one to two inches deep with the thicker cut end closest to the surface of the soil and you’ll have new plants in the spring. Don’t harvest leaves the first year. Give the plants a full growing season to get established.
Horseradish can be invasive, so be careful where you put it. Even small bits of root have the ability to sprout and start a new plant. I have heard plenty of tales of people who accidentally ran a tiller through a horseradish plant and ended up with a lot more horseradish that they ever wanted. If you just want a few plants to make your own horseradish sauce, this would be a great plant to grow in pots.