Growing Horseradish: 9 Things to Know


Horseradish is a popular condiment in the United States, usually used as a powder or as a paste or sauce. But what is horseradish, and where does it come from? And can you grow your own?

Horseradish is a cold-hardy plant that grows well in moderate climates. It needs rich soil and regular watering to reach its full pungency and is usually harvested after the first frost. The pungent flavor comes from a chemical reaction between enzymes that happens when the root is cut or grated.

The leaves are technically edible, but the distinctive flavor comes entirely from the root. Horseradish isn’t a difficult plant to grow at home for a fresh and delicious condiment. This post will highlight nine important things to keep in mind before planting horseradish in your home garden.

Photo of horseradish root next to a sprig of green leaves and a ground mound of horseradish on a white backdrop
Photo by Ledo

How Many Varieties of Horseradish Are There?

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The International Herb Association recognizes 30 different horseradish cultivars. Their primary differences are in their foliage. Different varieties are resistant to different pests. The roots of the plants are largely the same in flavor and appearance.

All the varieties are divided into two groups, “common” and “bohemian”. The “bohemian” types are more resistant to disease, although the “common” types tend to have better flavor. Most industrially-grown horseradish currently comes from the “bohemian” group. However, it’s difficult to find anything other than the variety “Variegata” if you’re a home gardener.

Does Horseradish Have Capsaicin? What Makes It Spicy?

Unlike peppers, horseradish gets its kick from an enzyme known commonly as mustard oil. There is no capsaicin in a horseradish taproot. The spiciness in horseradish is actually a small chemical reaction.

When you cut the plant, enzymes in the plant digest a chemical called sinigrin. That digestion creates the mustard oil as a byproduct. Once it’s exposed to heat or air, it starts to lose its pungency and develop a bitter taste. That’s why you should store cut or grated horseradish in vinegar; otherwise, it will lose its pungency.

How to Grow Spicier Horseradish?

The trick to getting spicier horseradish is to increase the size of the root. Pulling off the foliage will encourage root growth, and therefore increase the spice level. You can remove the top foliage of your plants several times throughout the season to keep encouraging that taproot.

Adjusting your fertilization can also help. Excessive nitrogen will lead to more foliage and less root growth, so cutting down on the amount of nitrogen in your fertilizer will give you a spicier root. Making sure the plant has enough water will also help. Dry plants have woodier roots that produce less flavor.

How to Grow Less Spicy Horseradish

On the other hand, if you leave the foliage alone, your horseradish will not be as spicy. If you leave the plant alone, it will focus its energy on spreading and creating leaves.

Additionally, a horseradish plant is usually spiciest in its first year. If you want to cultivate less spicy horseradish, you can wait to harvest the taproot from an older plant. It will continue growing for years if left alone.

The same aging principle applies to a root you’ve already harvested. The longer you wait to cut and use it, the less spicy it will be.

How Much Water Does Horseradish Need?

Horseradish is a hardy plant that doesn’t need much water to survive. However, keeping the roots well-watered will get you a better-quality root and prevent them from becoming too tough or woody.

If the roots are too moist, however, it will kill the plant. You should water your horseradish plant regularly and cover the roots with mulch in the summer to help them retain moisture. However, your soil should drain well. As a general rule, you want to give the plants 1-2 inches (2.54-5.08 cms) of water per week.

If you’re growing your plants in containers or pots rather than a garden, you may need to water them more often. Containers tend to dry out faster than a garden bed.

Photo of horseradish root with whiteish green shoots coming out of the top on a white backdrop
Photo by Galifax

Can Horseradish Grow in the Winter?

Technically you can grow horseradish in the winter months but the season you should plant your roots depends on your region and the temperatures there. Horseradish is a cold-hardy plant and prefers cooler weather, so if your climate experiences mild winters, you may do better planting in the early fall and growing your horseradish over the winter months.

Can Horseradish Grow in Desert Climates?

Horseradish can grow almost anywhere with full sun and well-draining soil. It does, however, prefer cooler temperatures in the 45 to 75 degrees Fahrenheit (7 to 24 degrees Celsius) range. If you are growing horseradish in a desert climate, it will do better as a late fall plant for harvest in the spring rather than a summer plant.

Growing horseradish in a desert climate will be difficult, as it harvests best after the first frost. Horseradish grown in warm desert conditions will not be as pungent as horseradish grown somewhere with a strong winter frost. It will not grow as a perennial in the desert, but you can grow it as an annual.

Can You Grow Horseradish Under a Grow Light?

Horseradish plants can thrive in full or partial sun. However, the temperature is more important to horseradish than light. Growing it indoors is incredibly difficult as the frost is important. You could use a grow light indoors to grow horseradish, but it would not be a very hardy plant, and the taproot would not have as much flavor and pungency as an outdoor plant.

You can start horseradish indoors before transplanting it to an outdoor area when the ground thaws. In that scenario, a grow light can be useful if you live in a climate with low sunlight in the late winter.

How to Know When Horseradish is Ready to Harvest

It’s best to harvest your horseradish after the first frost but before the ground thaws. The best flavor comes from roots that you dig up after the frost has killed all the foliage. Some people advocate for leaving the roots in the ground over the winter and digging them up in the early spring for better flavor.

Whenever you harvest, it’s important to dig up all of the roots, not just the taproot. Horseradish spreads incredibly fast, and any roots left in the ground will quickly take over as much space as they can. If you don’t mind horseradish taking over your garden, you can leave the small roots behind as your plants for the next season.

Closing Thoughts

While horseradish is hardy and flexible in terms of water and sunlight, it’s pickier about temperature. Growing a good, pungent horseradish requires a lot of patience and a solid frost. If your goal is to grow a super-pungent root, it’s important to limit foliage growth, and first-year roots will have a stronger flavor than plants left in the ground for multiple years.

Horseradish will thrive outdoors in most conditions but growing it indoors with a grow light or in a warm climate will limit your root growth and flavor potential. Growing it outdoors, however, carries a significant risk of spreading through your whole garden. Using containers or having a designated horseradish garden bed will help curb its growth.

Here are Some of my Favorite Gardening Products and Tools

Thank you for reading this article. I hope you found it helpful for growing some new plants in your home or garden. Here are some products I like that I hope you’ll also find helpful. These are affiliate links, and I am compensated for referring traffic. But in all honesty, these are the exact product that I use or recommend to everyone.

Soil: For high-quality soil, I really like Fox Farm Ocean Forest. I do all my growing in containers and this soil has worked great for me. I like how they use nutrient-rich contents like earthworm castings, bat guano, and composted crab and fish.

Fertilizer: Currently I am using a seaweed-based organic fertilizer call Neptunes Harvest. This is a great milder fertilizer option if you want to use something organic. If you want a more powerful fertilizer, I recommend Fox Farm Liquid Nutrient Trio, lots of people have had great growing success with this product.

Pruning Shears: Pruning shears are one of the most useful gardening tools to have because it’s important to prune your plants to keep them healthy. The pruning shears I recommend are the Gonicc 8’’ pruning shears. I like them because they are built sturdy and work both on bigger and smaller plants, so you don’t need to have multiple pruning shears.

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