Horseradish Plant: Hot Roots For Culinary Adventures

For people wondering, ‘what is horseradish’, here’s a fun fact: horseradish roots have been around since 1,500 BC! Horseradish is a pungent root vegetable that’s popularly used as a spice. The plants have been cultivated since time immemorial. In fact, they’ve famously been mentioned in Greek mythology, where the Delphic Oracle confessed to Apollo that horseradish roots are as precious as gold. 

Horseradish may not look like much, but it’s certainly a staple spice used in many households. What’s surprising about horseradish plants is that even when they contain the name “horse”, they’re in fact poisonous to those very animals!  

These perennials are so strong and resilient that they can thrive in almost any condition. Traditionally used as a natural remedy for coughs and colds, horseradish is definitely a prized plant to possess. Read on to find out how you can grow this versatile plant in your backyard!

Good Products For Growing Horseradish:

Quick Care Guide

Horseradish plant
The horseradish plant produces spicy, edible roots. Source: winhide
Common Name(s)Horseradish, red cole
Scientific NameArmoracia rusticana
Months to HarvestRoughly 6 months
LightFull sun to partial shade
Water:About 1″ of water per week
SoilLoamy soil with lots of organic content
FertilizerFertilize in spring if necessary, or use compost
PestsFlea beetles, crucifer weevils, caterpillars, root knot nematodes, beet leafhoppers
DiseasesRust, root rots

All About Horseradish

Horseradish plants in corner
Horseradish leaves are edible too, if a bit bitter. Source: UnconventionalEmma

Although the plant is commonly known as horseradish, it goes by the botanical name Armoracia rusticana. Sometimes, this plant is known as red cole. The peppery roots of this gorgeous plant have been as a condiment for more than 3,000 years. Its history and use of horseradish roots can be traced back to the Middle Ages, where people in Europe used it to season pieces of meat. 

For those wondering, “why is it called horseradish?”, well, the perennial found its name through an interesting process. In German, horseradish came to be known by the name, “meerrettich” or sea radish. This is because the roots grew by the sea. However, many english-speaking people began mispronouncing the word “meer” and started calling it “mareradish”. 

And, so, the plant eventually came to be known as horseradish. The word “horse” indicates the coarseness and the large size of the plant. Horseradish is native to Western Asia and southeastern Europe. It’s also commercially produced in many US states like New Jersey, Wisconsin, California, and Illinois. 

It belongs to the same family as other cruciferous vegetables like cabbage, broccoli, mustard, and wasabi, the Brassicaceae family. Horseradish root is used both as a condiment and a spice. It can grow up to 4.9 feet or 1.5 meters tall and is primarily cultivated for its white, large tapered root that’s perfectly edible. 

Those who have grown horseradish will know that the plant is quite aesthetic. Its leaves have a unique growing pattern; they form a distinctive rosette that sprouts into single or multiple stems. Each leaf has long petioles that have a crinkled or smooth texture. 

Horseradish leaves are dark green in color and range between 11-39 inches in length. But horseradish really is known for its large, fleshy, and extremely thick taproot. It is cylindrical in shape and grows up to 19 inches in length, making it a prized plant for avid gardeners. 

The horseradish flower is white in color and is produced on racemes. Overall, growing horseradish can take up to an entire year, so if you’re planting it in fall, you can expect the harvest during the fall season of the next year. This is one reason why wild horseradish is grown as an annual perennial. 

Horseradish is a root crop and is effectively grown through its tuberous roots as well as from seed. Armoracia Rusticana has been popularly used in the culinary world. The flesh of the horseradish is crushed and grated to make a sauce or used as a spice. Horseradish root has a pungent taste, allowing it to be used in place of true wasabi. Horseradish sauce, famously eaten in the UK and Poland, is made from grated horseradish and vinegar. To ease the heat, it’s occasionally mixed with sour cream. This sauce is also used in salads, sandwiches, and served with roast beef. 

Planting Horseradish

Horseradish seedling
Horseradish leaves have slightly toothed edges. Source: Danny Baza Blas

Growing horseradish is easier than you think. Horseradish roots are cold-hardy, allowing them to adapt to a wide range of weather conditions. Here’s a quick breakdown of when, where, and how to grow horseradish. 

When To Plant

If you want new plants, you need to carefully choose the right soil and temperature conditions to ensure a successful harvest. The best time to start horseradish, especially in the United States, is spring. 

Whether you’re growing horseradish from the crowns or the roots, it’s best to set them up nicely a few weeks prior to the last frost date. Make sure that you’re planting in USDA hardiness zones 3 to 9. This will ensure that the horseradish roots germinate successfully. 

If you’re growing horseradish in containers, the best time to transplant them to an outdoor garden is during the early growing season, just before new growth kicks off. You can also replant them once the season ends when you might be harvesting horseradish roots. 

Where To Plant

Deciding the location is extremely crucial. Horseradish grows best in well-drained but moist, silty soils. These can be naturally found in river bottomland. However, if you’re growing them in your backyard, you can use a growing field of sandy loam or enriched clay. 

Be mindful that these plants need fertile soil with a neutral pH to grow successfully. Be sure it’s in full sun conditions for best growth. A 3-inch layer of organic mulch will keep the soil moist and reduce weed growth, but keep it a few inches away from the base of the plant.

Horseradish plants have a habit of spreading, so you won’t need more than two root pieces to produce enough for your entire family.

When planting, prepare the soil at least 10-12 inches deep and add compost and sand to keep the soil rich and loose. If planting in raised beds, your plants should be spaced 18-24 inches deep to ensure ample room for root development.

How To Plant

You can grow horseradish from seeds by sowing them in the ground and covering them with a small amount of loose compost and soil. Once the seedlings appear, you can thin them out, ensuring that they are at least 1 foot apart.

Dig holes at least 8 inches deep and 12 inches wide. Plant it at a 45-degree angle, with the larger end facing the top of the soil line. Cover the hole with 2-4 inches of soil up till the crown and water the plant. 

Alternatively, you can also grow horseradish plants in pots that have good drainage holes. The containers should also be deep enough to stimulate healthy and deeper root growth of at least 24-36 inches.

Growing Horseradish

Healthy horseradish plants
Some healthy horseradish plants. Source: UnconventionalEmma

Now let’s discuss the crucial details of growing and maintaining the horseradish plant! These care guidelines should ensure success.

Sun and Temperature

Horseradish needs full sun to grow although it tolerates partial sun well. Give young plants a minimum of 6 hours of daily sunlight, more if possible. It prefers a temperature between 45-75 degrees Fahrenheit. 

Horseradish is cold-hardy, but it’s extremely sensitive to excessive heat. Keep an eye on the temperature. It shouldn’t exceed 75 degrees Fahrenheit. If it does, provide some shade by hanging shade cloth over the plants, or move them to a cooler location.

Water & Humidity

Horseradish can tolerate some neglect. Watering about an inch of water once a week is enough, but short periods of drought are acceptable. Water only the soil to reduce the risk of plant diseases like rust.

Soil

The perennial can be grown in rich loamy, sandy, or clay soil, so long as it’s loose and well-aerated. If given a preference, your plants will prefer the soil a bit silty.

It requires fertile soil so make sure to enrich the ground with compost. The ideal soil pH level should be around 6.0 to 7.5. Be sure your soil drains off excess moisture well, and that water doesn’t pool on the soil’s surface.

Fertilizing

Fertilize in the spring, using a low-nitrogen and high-phosphorus fertilizer for larger, healthier roots. If you’ve amended the soil heavily with compost, you may be able to skip fertilizer entirely!

Pruning

Pruning horseradish is mostly unnecessary. It’s mainly done to keep the suckers from inhibiting the growth of the main shoots. Remove the sucker leaves when they’re 6-8 inches long. These leaves grow outside of the plant’s crown.

Make sure to trim those only and leave the tight bunch of leaves that’s growing right from the crown’s center. That’s where you want growth to continue!

Propagation

Horseradish can be propagated from seed or from root segments. 

From root segments, simply leave some of the roots in the ground when you harvest. New plants will form from those roots. If you’re overwintering them in the ground, be sure to cover the roots with a thick layer of compost to reduce the likelihood of them freezing.

You can also sow seeds in well-cultivated, compost-rich soil. Depending on the conditions, they’ll begin to sprout in 7-15 days. 

Harvesting and Storing Horseradish

Half peeled horseradish root
A partially-peeled horseradish root. Source: cv47al

The harvest and use of your produce is the best part, and when you grow horseradish, you’ll be able to have a great crop for next year too!. Here’s a quick guide on when to harvest horseradish and how.

Harvesting

The ideal time to harvest will be in in the fall. For me, that’s early October when the first frosts have already damaged the leaves. Using a clean digging fork, carefully lift and loosen the soil around the horseradish plant. Once all the sides have been loosened, grab the plant and gently tug it away from the soil. Be careful not to damage the roots. 

Storing

Whole horseradish root should be stored without washing or peeling. Wrap them in dark-colored plastic to block out light and store them in the refrigerator. It will usually last for about two weeks this way.

You may also peel and grate the root, mixing it with vinegar. Be forewarned, horseradish releases an isothiocyanate aroma that can be quite powerful when you’re grating it up! If you’re the type who cries when chopping onions, you may want to do this step outside where you have fresh air. A food processor can also help you break it down.

Quickly fill a container with your grated horseradish and add white wine vinegar. This provides enough acidity to preserve the potent root in the refrigerator for up to two weeks. Avoid using cider vinegar as it will discolor the white grated horseradish.

You can also cut your horseradish into one-inch chunks and put it in a freezer storage bag or vacuum bag. Store it in the freezer until you need to use it, and thaw before using. Grated horseradish only lasts a couple weeks in vinegar and will quickly lose its potency, so freezing the excess allows you to enjoy it year-round.

Troubleshooting

Horseradish plants with some bug damage
Some pests will snack on horseradish leaves. Source: graibeard

Horseradish is fairly hardy stuff, but it is vulnerable to a few pests and diseases. Let’s go over those now!

Growing Problems

Overwatering is a danger for horseradish. Excess soil moisture can promote root rot. But be sure not to under-water it as well, as roots with low moisture become woody and bland. 

Protect your plants from excess heat to avoid the greens wilting. During the height of summer, this may require the use of shade cloth.

Pests

A number of pests nibble on the leaves of horseradish. Among those are flea beetles and caterpillars. While the damage is mostly cosmetic with flea beetles, caterpillars can strip a plant of its foliage. Use a bacillus thurigiensis spray to eliminate caterpillars, and pyrethrin sprays to get rid of flea beetles. Neem oil should prevent both.

Where the larger concern comes into play is pests which damage those spicy roots. Crucifer weevils, which are the larvae of certain types of flea beetle, can bore into the roots. Root knot nematodes may cause disfiguration and damage to the roots as well.

Pyrethrin will deal with the crucifer weevils as well, but you’ll want to apply beneficial nematodes to take out root knot nematodes.

Finally, the beet leafhopper doesn’t do severe harm to the plant itself, but is a vector for a particular plant disease. It transmits the pathogen that causes brittle root disease and curly top. Keeping these leafhoppers at bay can be done with insecticidal soap, or failing that, the pyrethrin you use against the flea beetles.

Diseases

Some forms of rust fungus can impact your plants as well. Apply sulfur powders or neem oil to the leaves to prevent it, or use a copper-based fungicide to clear up outbreaks of white rust. 

If the soil is too wet, various rots can impact the roots of your plant. Be sure not to overwater, and make sure that water does not pool up on the soil’s surface.

Frequently Asked Questions

Q: Can you eat the leaves of the horseradish plant?

A: Horseradish plants are mainly grown for their roots. However, their leaves are so edible with a peppery, sharp, and slightly bitter taste. You can cook them or eat them raw. 

Q: Can you plant horseradish from the grocery store?

A: If they’re very fresh, you can. Look for healthy horseradish roots at your grocery store or nursery. Cut off the bottom 2” of your roots and allow them to dry out thoroughly for a couple days to form a callous on the cut edge. Then, plant as if they were a new plant about 1” under the soil’s surface. Once it begins to grow again, it’ll develop new leafy growth.


The Green Thumbs Behind This Article:

Lorin Nielsen
Lifetime Gardener

Clarisa Teodoro
Researcher

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