If you’ve been wanting to try homemade horseradish sauce on your roast beef sandwiches, this is your sign to plant horseradish this year. Homemade horseradish flavor is much brighter and fresher than anything you can buy. And the plant is easy to grow (maybe too easy)!

Horseradish (Armoracia rusticana) is a perennial hardy in USDA zones 3-9, and while the entire plant is edible, we grow it for the roots. The plants are an attractive tuft of foliage with long leaves, reaching 2-3 feet tall and wide. 

Horseradish loves cool weather, and does best in areas that receive winter frosts. The above-ground portion grows quickly in summer, but the roots put on their growth in the autumn. While the big root we harvest for the kitchen grows pretty much straight down, side roots spread out and can send up new vertical shoots, which is how this plant spreads. Like mint, it can start to escape if not kept under control by harvesting or contained below ground, such as in a bottomless five-gallon pail.

Site Preparation

Like other root crops, horseradish needs a spot with deep, loose soil. While it grows best in full sunshine, it will tolerate partial sun, although harvests will be lower. Good drainage is important.

To prepare your site before planting horseradish:

• Loosen the soil with a spade to a depth of 10 inches, or about one shovel depth. If you can get a bit deeper, that’s even better.

• Work in a healthy amount of compost to improve soil structure and nutrient-holding capability.

• If you can, let the freshly worked soil settle for a couple of days before you plant. 

While well-aged and composted manure is an excellent soil amendment for most plants, avoid adding fresh or only partly composted manure when planting horseradish. Manure that has not been fully composted will provide too much nitrogen, causing an impressive amount of top growth, but will result in branched, low-quality roots that are difficult to use. If it still has chunks that look like manure, it’s too fresh yet to use on horseradish.

Horseradish grows well in slightly acidic soils, with a pH of 6.0-7.0. That’s about what most of our vegetables do well at. If your soil doesn’t need a pH adjustment for veggie gardening, it’s probably fine for horseradish.

Planting horseradish 

After choosing and preparing your site, it’s time to get planting.

Horseradish sets, or roots, are best planted in early spring, as soon as the soil is workable, to take full advantage of the growing season. It’s okay for them to go in the ground before your last spring frosts, as they’ll take a while to pop up. If you order online, they’re typically shipped to arrive at about the right time for planting at your location, plus or minus a couple of weeks.

• Prepare a hole and plant the horseradish root at a 45 degree angle. If the root has one flat cut end and one end with an angled cut, plant the angled end down. If both are the same, plant the root with the smaller end down. If planted horizontally, they may sprout from many locations along the length of the root and become crowded.

• Space horseradish plants about 18-24 inches apart. 

• Plant the roots so the top of the root (remember to place it at a 45-degree angle) will be about 2-3 inches below the ground level. Refill the hole and gently firm the soil in place.

• Unless your soil is quite dry, hold off on watering until the first sprout has poked above the surface. Just like a potato, the horseradish root has enough energy to start growing roots and shoots.

Planting horseradish in a container

Growing horseradish in a container works quite well, provided the pot is large enough. You’ll need a pot that is ideally at least 18 inches deep to allow room for the main root to grow. Choose a container with good drainage, and fill it with potting mix, not garden soil, then plant the horseradish as above. 

Growing Needs

Horseradish is a tough plant, and once it gets going, you’d have a hard time killing it with neglect. It does need to be kept weed-free, especially in the early part of the season when the plants are small. 

Provide weekly waterings, about an inch per week, if rainfall is insufficient. Mulch around the horseradish plants to hold soil moisture and keep weed pressure down. Compost, shredded leaves, clean (untreated) grass clippings, or pine straw are all excellent materials to use. 

Fertilizer isn’t needed for horseradish grown in fertile, loamy soils, but if your site is sandy, or if growing in a pot, you’ll need to apply a low-nitrogen fertilizer (the first number is much lower than the second and third numbers, like a 5-10-10) once a month during the growing season.

Many horseradish growers will “lift” the roots and remove some of the side roots once or twice during the summer, which makes the central root we harvest larger. However, it isn’t strictly necessary. Lifting horseradish involves partially digging up the plant, trimming side roots, and replanting. Prune off suckers that form above ground, leaving only 3-4 stems at the center of the crown.

Harvesting horseradish

Wait to harvest horseradish until the cool weather of autumn when the frosts have killed the foliage. Not only do the roots put on most of their growth later in the season, but the flavors are brighter and more intense. Summer-harvested horseradish can be underwhelming. 

Similar to harvesting potatoes, the key here is to start farther from the plant and work your way in. You’ll dig up the entire plant. Horseradish roots can spread out, and you’d rather choose where to cut once you can see the entire clump than to accidentally sever the main root with your shovel.

Pull the entire root clump free, and trim off the tops. Cut the bottom and side roots off the main root and set them aside. You’ll replant those in spring for next year’s plants. For those roots you save, cut the tops square and the bottoms at a 45-degree angle, and you’ll have an easier time figuring out which end goes up next year.

Store the root cuttings for next year in a small bucket of moist sand in a place that stays refrigerator temps, about 32-40 degrees, and keep them in the dark. 

Some gardeners will harvest horseradish the first year, and others prefer a larger root and wait until the second year. 

Storing horseradish

The best horseradish sauce is made fresh, and keeps only a few weeks in the refrigerator before it starts to fade. But the roots can be kept whole, ready to be used to make a fresh batch every month or so.

To store the harvested roots, wrap them in perforated plastic and keep them in the refrigerator or where you store the smaller roots for next year. Keep them out of the light, or they may turn green. Remove a root and grate it whenever you are ready to make a fresh batch of the spicy condiment.

Of note, as you will surely read when you look up recipes for horseradish, fresh horseradish is pungent. Grate it outside where the fresh air can take away the fumes. If you think onions make your eyes tear up, horseradish can be flat-out overpowering.

Horseradish pests and problems

The most common pest issue for horseradish is the flea beetle, which lays eggs on the leaf stalks. The larvae hatch and eat their way into the stalk, which can kill the leaf. If flea beetles are a problem, floating row covers can work to keep the adults from reaching the plant to lay eggs. If you see egg clusters on your horseradish, smush ‘em.

Normally, the biggest problem for gardeners with horseradish is keeping it from taking over. Harvesting annually does a good job of keeping this spreading plant under control. Dig up the entire plant, including the side roots, when harvesting, and only replant as many as  needed. The roots spread laterally, so planting it in a raised bed, or inside a tube-shaped container like a bucket without a bottom, can also help with control. 

Several gardeners have noted that one should never till the area where horseradish was planted, as every little piece of root chopped up by the tiller will sprout a new plant.