Armoracia
( am - or - AY - see - ah )
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At-A-Glance InformationCommonly referred to as Horseradish (and historically as Stingnose), these perennial plants (sometimes grown as annuals) are known worldwide as a spice or condiment. These plants have been cultivated since the beginning of human history, and both roots and leaves were used in many cultural traditional medicine practices. Grow these plants as parts of herb or vegetable gardens, or simply have a few plants in mixed beds or borders as filler.
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Armoracia Species and Varietals
The genus Armoracia is a member of the plant family Brassicaceae, making it a relative of plants like Mustard, Wasabi, Broccoli, Cabbage, and Radish. There are just three species in this genus. Horseradish plants were first brought into the American markets around 1806, and was being grown commercially by 1850. About 60% of the world's horseradish supply is grown in and around Collinsville, IL. The best growing zones for Horseradish plants are A1, A2, and 1-22. To find your zone, click here: Zone Map.
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Armoracia rusticana (Horseradish) Native to southeastern Europe and western Asia, this species is widely cultivated for its large underground storage root. It is the type species of the genus, and can reach up to 5 feet tall when mature and in bloom, and produces bright green leaves. Cultivar 'Variegata' produces leaves that are beautifully marked with white. |
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Armoracia sisymbrioides Native to Asia, this species was formally described in 1821, and is very similar in looks to Horseradish. Its root is used as a culinary herb and as a medicinal plant in its native range. Flowers are small and white with yellow centers. |
Caring for Armoracia
Plant Horseradish in a spot in the garden that receives full sun exposure; Between 4 and 6 hours is ideal. If these plants are not grown in sunny enough conditions, the growth of the root will slow considerably. Ensure that soil is well-draining and fertile, and that there is enough vertical space under the soil surface for the large taproot to develop well. If there are any hardpan layers of soil in the garden, they will stunt the growth of the root. The ideal soil pH for growing horseradish is between 6.0 and 7.5. These plants will spread vigorously if allowed to; it is recommended to grow them in a container or bury a plastic tub around it in the soil. The best time to plant horseradish sets (root cuttings) is in springtime as soon as the last frost of the year has passed and soil has become workable. Break up soil to a depth of between 8 and 10 inches in the planting area, and mix in generous amounts of compost or other organic material. Water the soil and then let it settle for a few days before planting. When planting sets, space them about a foot apart and cover them with two to three inches of soil. After planting, mulch around the area to suppress weed growth, increase soil moisture retention, and maintain a constant soil temperature.
Horseradish plants do not need any fertilizing during the growing season, as long as soil is fertile and was amended with plenty of compost or organic matter at planting time. To encourage a healthy, large root to develop, it is suggested that when the largest leaves on the plant reach between 8 and 10 inches long, that the plant should be lifted out of the soil. To do this, remove the soil from the upper ends of the main root. Leave roots at the lower end undisturbed. Raise the crown and remove all but the best crown of leaves. Then, rub off all smaller roots from the crown and sides of the main root, leaving only those at the bottom. Then, return the root to its original position in the soil and fill in the soil around it. Mulch over the top. Repeat this process again six weeks later.
Harvesting Horseradish Plants
Horseradish roots will put on the most growth during late summer and early fall in preparation for the plant's dormancy period over the winter months. Harvesting can be put off until right before the ground freezes. To bring roots out of the ground, dig a trench between 1 and 2 feet deep along one side of the row, then gently work around the roots to dig them out. Trim off the green tops so that there is just about an inch left, and trim off side and bottom roots and root hairs. Save any roots that are eight inches or longer for the next season's planting stock. Cut roots squarely across the top, sloping towards the bottom, to indicate which end to point upwards when planting time rolls around again. If storing roots to replant in springtime, store them in moist sand and overwinter them in a cold area (between 32 and 40 degrees Fahrenheit). Do not expose the roots to sunlight, otherwise they will become green. If the right storage conditions cannot be met, harvest horseradish in springtime rather than in fall. Dig up the roots as soon as new growth appears in springtime, and replant the lateral roots at the same time. Roots that are left in the ground for two growing seasons become stringy and woody (unpalatable). To store horseradish for future use, it can be kept in a plastic breathable bag for a few months in the refrigerator.
The green leaves of Horseradish plants, like the roots, are edible. When crushed, they give off the same smell as the root, and can be harvested weekly if needed. The only caveat to this process is that the more leaves that are taken from the foliage of the plant will mean less photosynthesis, which translates to lower production of the carbohydrates that are stored in the root. Harvesting the leaves can lead to a slightly smaller root, but also have a lot of flavor themselves and if responsibly harvested, can be taken from the same plants that produce harvested roots. After removing leaves from the plant, bring them inside and remove the center stalks, similar to the preparation of Kale. Although the leaves do have an intense flavor similar to the root, and can be bitter, they are fantastic when combined 50/50 with another palatable green like spinach. The flowers are also edible, and are often used as garnish.
Horseradish plants do not need any fertilizing during the growing season, as long as soil is fertile and was amended with plenty of compost or organic matter at planting time. To encourage a healthy, large root to develop, it is suggested that when the largest leaves on the plant reach between 8 and 10 inches long, that the plant should be lifted out of the soil. To do this, remove the soil from the upper ends of the main root. Leave roots at the lower end undisturbed. Raise the crown and remove all but the best crown of leaves. Then, rub off all smaller roots from the crown and sides of the main root, leaving only those at the bottom. Then, return the root to its original position in the soil and fill in the soil around it. Mulch over the top. Repeat this process again six weeks later.
Harvesting Horseradish Plants
Horseradish roots will put on the most growth during late summer and early fall in preparation for the plant's dormancy period over the winter months. Harvesting can be put off until right before the ground freezes. To bring roots out of the ground, dig a trench between 1 and 2 feet deep along one side of the row, then gently work around the roots to dig them out. Trim off the green tops so that there is just about an inch left, and trim off side and bottom roots and root hairs. Save any roots that are eight inches or longer for the next season's planting stock. Cut roots squarely across the top, sloping towards the bottom, to indicate which end to point upwards when planting time rolls around again. If storing roots to replant in springtime, store them in moist sand and overwinter them in a cold area (between 32 and 40 degrees Fahrenheit). Do not expose the roots to sunlight, otherwise they will become green. If the right storage conditions cannot be met, harvest horseradish in springtime rather than in fall. Dig up the roots as soon as new growth appears in springtime, and replant the lateral roots at the same time. Roots that are left in the ground for two growing seasons become stringy and woody (unpalatable). To store horseradish for future use, it can be kept in a plastic breathable bag for a few months in the refrigerator.
The green leaves of Horseradish plants, like the roots, are edible. When crushed, they give off the same smell as the root, and can be harvested weekly if needed. The only caveat to this process is that the more leaves that are taken from the foliage of the plant will mean less photosynthesis, which translates to lower production of the carbohydrates that are stored in the root. Harvesting the leaves can lead to a slightly smaller root, but also have a lot of flavor themselves and if responsibly harvested, can be taken from the same plants that produce harvested roots. After removing leaves from the plant, bring them inside and remove the center stalks, similar to the preparation of Kale. Although the leaves do have an intense flavor similar to the root, and can be bitter, they are fantastic when combined 50/50 with another palatable green like spinach. The flowers are also edible, and are often used as garnish.
Propagation
Armoracia can be propagated either by dividing root sections or by seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the root cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant, especially if the parent plant is a hybrid. To propagate your Horseradish plant, follow the instructions below:
Propagating Armoracia by Seed
Propagating Armoracia by Division
This type of propagation is relatively simple; you will need a clean shovel, mulch, fresh soil (any kind will do, though it does need to be well-draining), compost and pots (12 inch pots will do, and these are only necessary if you will be saving divided plants for transporting elsewhere). Division is best done in fall. To propagate by division, follow these steps:
Propagating Armoracia by Seed
- Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows.
- Harvest your seeds. Typically, it is best for the harvesting of horseradish roots to cut off all flowering heads as they appear, but to collect seeds, at least one plant will need to be allowed to go to flower. Once flowers have faded and turned brown and crunchy, which typically is in late fall, the seeds can be collected. Cut off entire flower heads and place them in a paper bag. Then, shake the bag to encourage seeds to emerge from their faded flowers.
- In January or February, water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 7-15 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
- Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
- Alternatively, horseradish seeds can also be direct-sown in the garden any time between March and the middle of summertime.
Propagating Armoracia by Division
This type of propagation is relatively simple; you will need a clean shovel, mulch, fresh soil (any kind will do, though it does need to be well-draining), compost and pots (12 inch pots will do, and these are only necessary if you will be saving divided plants for transporting elsewhere). Division is best done in fall. To propagate by division, follow these steps:
- Gather your materials. Using a shovel, dig up your existing plant. Start from the outside and work your way in to avoid damaging the tuber roots. Once you have worked it up out of the ground, lay it out.
- Start to tease apart the roots with your gloved fingers. Once the roots are untangled, separate your plant into segments, ensuring that each one has at least one thick tuberous section.
- Prepare your pot(s) or new planting site(s) with amended, well-draining soil. You can either bring in new soil or simply amend your existing soil with compost to complete this task. Then, plant your divided tubers about an inch under the soil surface and water thoroughly.
- Apply a thick layer of mulch over the new planting to protect it from cold weather as it acclimates to its new home. Then, enjoy watching it sprout.
Horseradish seed heads will dry out and turn brown when they are ready to release their seeds.
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Horseradish seeds are tan to light brown in color.
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Problems and Pests
Horseradish plants are typically pest and disease free, though they can have problems with the following from time to time:
- Bacterial Leaf Spot
- Brittle Root
- Cercospora Leaf Spot
- Ramularia Leaf Spot
- Cabbage Looper
- Flea Beetle
Gallery
Amoracia rusticana 'Variegata'.
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It is suggested to grow horseradish plants in raised beds or containers to prevent them from spreading too much.
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Pieces of horseradish roots for replanting are sometimes called 'thongs'.
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Horseradish is a popular condiment for many meat dishes.
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Armoracia flowers are small and white, similar to those of other Brassicas.
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Horseradish in a home garden planted alongside Garlic Chives.
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Videos
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Harvesting and preparing Horseradish.
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How to grow horseradish in the garden.
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Resources
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