How to Grow Horseradish
Horseradish is a hardy perennial in the Brassicaceae family believed to be native to parts of Europe and Asia and brought to North America by colonizers. While it is an attractive plant with white flowers and can be used in an edible, decorative border, it is most often grown for its large, flavorful taproot. Interestingly, horseradish root has almost no scent when intact, but, when cut or grated, the damaged cell walls release an enzyme (myrosinase), which causes the break down of a glucosinate called sinigrin. This is the same process that gives mustard made from black mustard seeds its distinct bite.
The Roman naturalist and writer, Gaius Linius Secundus (AD 23-79), generally known as Pliny the Elder or just Pliny, included horseradish in his works as a medicinal plant that did not have culinary uses. By the Middle Ages, horseradish was being used both for medicine and cooking, particularly as a condiment for meats. It is also one of the Maror (bitter herbs) options commonly used on traditional Passover Seder plates.
Throughout the ages and continuing today, horseradish is used in home remedies and by herbalists to treat an array of ailments, such as sinus infections, kidney stones, bladder infections, indigestion, lung ailments, gout, intestinal worms, high blood pressure, and joint pain.
Most people growing horseradish in modern, backyard gardens intend to use the root to make spicy, flavorful condiments, but you can also eat horseradish leaves by adding raw leaves to salads or cooking them in your favorite stir fry or soup.
It should be noted that horseradish plants are considered highly toxic to livestock, such as horses, cattle, goats, and sheep, and they are considered potentially toxic to other animals, such as dogs and cats.
Human consumption of horseradish leaves is generally considered safe in small to moderate quantities, but the consumption of large amounts of horseradish leaves or any part of the horseradish plant should be avoided.
How to Grow Horseradish: Starting Horseradish Plants
Horseradish plants are not started from seeds. Instead, they are started from sets, which are secondary roots. You can purchase horseradish sets online or from your local nursery, and you can even start your plants from roots purchased at the grocery store or farmers market. Backyard gardeners plant horseradish in either early spring or late fall with early spring generally considered the best time to plant.
When you buy your sets from a nursery, they should already be cut and ready to plant. If you purchase roots at a farmers market or grocery store, cut the top part of the root off to use for cooking or home remedies, and keep the bottom part to plant in your garden.
Horseradish can be grown in just about any soil type, but it usually does best in loamy soil. For those of us working with the clay soil found in many parts of Southern California, it is a good idea to add organic matter, such as compost, before planting your sets. You may also want to test your soil to see if additional amendments are necessary, since you will have the most satisfactory results growing horseradish in soil with a pH between 6.0 and 6.8.
Dig a hole at least one foot deep, add compost, and place the root in the hole at a 45-degree angle with the larger end or crown resting an inch or two below the ground. If you are planting a crown instead of a root, make sure the leaves are above ground. Fill the hole with soil and water the plant thoroughly.
Most people need just one plant to supply enough horseradish for their family, but if you have a large family or are particularly fond of horseradish, you may want two or three plants, which should be planted about 24-30 inches apart.
How to Grow Horseradish: Where to Plant Horseradish
Gardeners can successfully grow horseradish in the ground, raised garden beds or containers. Because it can become invasive, some gardeners prefer to control its tendency to spread by growing horseradish in a container, which should be at least about 15 gallons in size. Make sure the pot is at least 24 inches deep – preferably 36 inches – so that the root system will have plenty of room to grow.
Horseradish grows quite well in containers, so if you have limited space or are worried about its invasive nature, containers are the way to go. Plus, this gives you the option of moving your horseradish for it to receive more or less sunlight throughout the day and will make it easier to harvest the roots.
If you choose to grow it in the ground or a raised garden bed, be sure to plant it in full sun or partial shade in an area where its invasive nature or large root system will not disturb other plants.
If you are planning to grow your horseradish as a perennial, be sure to pick a spot where it can continue to grow for years to come.
How to Grow Horseradish: Caring for Horseradish
As your horseradish begins to grow, you will notice several shoots coming up through the soil. Remove most of the shoots to focus on growing one good taproot. You will also need to pull weeds and suckers regularly. When the plant begins to flower, you can leave the flowers to enjoy the extra color in your garden, or you can remove them to encourage the plant to focus its energy on growing the taproot.
Once established, you will need to water your horseradish once each week. When it is particularly dry or hot, you will need to water it twice each week. When growing horseradish in pots, you may need to water more often.
Horseradish needs very little care to thrive, but it is beneficial to side dress your plants with a little compost a couple of times between planting and harvesting. This will help the soil retain moisture and will add nutrients back into the soil.
Horseradish roots are usually not affected by pests, but keep an eye out for aphids on the leaves, which will need to be removed.
How to Grow Horseradish: Harvesting and Storing Horseradish
Although it is a perennial herb, most gardeners prefer to grow horseradish as an annual. When doing so, you will harvest the entire plant each year. When growing horseradish in this manner, be sure to set aside some roots to save for next year’s planting.
Your horseradish should be ready to harvest approximately 150 days after planting, give or take a week or two. You can harvest it in either fall, winter or spring. If you happen to live in an area where the temperature drops enough to have a first frost in fall or early winter, it is best to harvest it after this first frost.
Loosen the ground around the plant before gently removing the entire plant from the ground. Any bits of the root system left behind will become new horseradish plants, so if you are growing horseradish as an annual, you will want to be sure to remove the entire root system. However, you can keep some roots in the ground if you would like to continue harvesting horseradish into winter. You can even harvest remaining roots in spring at which time you can also move any horseradish plants that have spread.
If you want to grow horseradish as a perennial, harvest the plant and main root, but allow some of the secondary roots to remain in the soil. These roots will become new horseradish plants for next year’s harvest.
Harvested roots should be rinsed, dried, and stored in the refrigerator in an airtight container, such as a mason jar. When stored in this manner, your horseradish should keep for about four to six months.
You can also clean, peel, and grate your horseradish to store it in the freezer for future use. Keep in mind that this process will cause the horseradish root to lose some of its pungency.
If you plan to use the leaves, they should be used fresh and not stored. If you are not going to use them, add them to your backyard compost bin.
When using fresh horseradish, cut off and peel only the amount you need. Dip the cut end of the remaining root in lemon juice or vinegar and place it an airtight container in the refrigerator. Once you have peeled or grated a section of horseradish root, it should be used right away or stored in an airtight jar in a brine made from water, vinegar, and salt. Your grated horseradish should be okay to use for about two weeks when stored in the refrigerator in the brine.
How to Grow Horseradish: Horseradish Recipes
Before you start peeling, grating, and using your horseradish in recipes, you need to know that working with fresh horseradish can be much more tearful and sinus-irritating than any onion you have ever cut. You will want to either peel and grate it outside or, at the very least, open some windows for proper ventilation before cutting into a horseradish root in your kitchen.
The second thing you need to know about working with horseradish is that you can control the spiciness of your prepared horseradish by how you time placing the grated root in vinegar. Vinegar stops the enzyme process that breaks down the sinigrin and releases mustard oil; therefore, the longer you wait to place the horseradish in vinegar, the stronger the flavor will be. For milder horseradish, place the grated root in vinegar right away. For stronger horseradish preparations, wait three to four minutes before adding vinegar.
The Horseradish Information Council (horseradish.org) recommends placing small cubes of peeled horseradish in a blender with water, blend to the desired consistency, and add two to three tablespoons of white vinegar or lemon juice and ½ teaspoon of salt per cup of horseradish root. You can then store this mixture in an airtight jar in the refrigerator.
You can add this prepared horseradish mixture to various condiments or use it in recipes to create your own condiments with a kick. For example, add ½ teaspoon of prepared horseradish to one cup of mayonnaise for use on hot sandwiches or add ½ teaspoon prepared horseradish to ½ cup ketchup for cocktail sauce. You can also add ½ teaspoon to a cup of sour cream for a tasty sauce to use on meats, or add some fire to your next Bloody Mary by adding ½ teaspoon horseradish to the recipe.