Although not a common ingredient in home kitchens, most are aware of the humble horseradish, a root vegetable used as a herb for its pungent flavor. Whether you can it or grate it fresh, there is nothing quite like the quintessential horseradish taste – strong and overpowering, but undeniably delicious at the same time. This taste is even better at its freshest: straight from the garden. Horseradish is a popular perennial vegetable due to its prolific growth. In fact, horseradish grows so well without any care, it is often labeled invasive. You’ll have far more trouble getting rid of the plant (if you ever actually want to) than when you actually plant it. Besides taste and incredible ease of growth, this plant also comes with a wide range of health benefits, used in ancient medicine hundreds and thousands of years ago. Growing this plant in your own backyard will not only add diversity to your diet, but to your garden too.
Plant History
This root vegetable goes back to ancient times, with Greek, Egyptian, and Roman history. Like many common herbs and spices with medicinal benefits, horseradish history goes back centuries, further than the historical record of the plant. The ancient history of horseradish is shrouded in myth and miscommunication – such as the belief that it was a prominent herb in Ancient Egypt. However, what we do know about its history is no less fascinating. The written history of horseradish first appears in Ancient Greece, where the root was prized for its medicinal value. Roman Pliny the Elder recommended the plant in his famous work Natural History. It also features in popular Greek Mythology, where the Oracle of Delphi is believed to have told Apollo that horseradish is worth its weight in gold.
Early consumption was mostly medicinal, especially during the Middle Ages. It was used to treat a myriad of ills, from coughing to digestive issues. Due to increased travel during the Renaissance and the Age of Exploration, the plant spread to the rest of Europe around the 15th and 16th centuries. Here, it gained a new value as a spice and condiment, used alongside meat dishes for its intense flavor. In the 1600s, horseradish was most popular in Germany, Scandinavia, and Britain. Around the same time, horseradish was transported from Europe to North America, where it gained the same level of popularity. Common in 18th century home gardens, records show it was even grown by George Washington and Thomas Jefferson. Horseradish remains popular 200 years later. It is still part of Jewish tradition, on the Passover Seder plate, and continues to be used in herbal remedies. By planting horseradish in your own backyard, you can preserve a little piece of this history.
Cultivation
Spicy horseradish is considered invasive to some people, as it is near impossible to get rid of. Horseradish is cultivated for its long roots and a special chemical makeup that gives the plant a spicy kick. The root contains glucosinolates that break down to form isothiocyanates when the tissues are damaged, like when grating or chopping. Most commercial production occurs in Europe, where this vegetable is most often used. When cultivated in gardens, horseradish can become invasive. This is due to the aggressively spreading tap roots that burrow deep into the ground. Older roots, although largely woody and inedible, make way for the spread of new, tender roots that spawn new leaves every season. Even the smallest piece of horseradish root left in the ground can grow into a fully-fledged plant, making it incredibly difficult to completely remove once planted. Gardeners attempt to control this growth by planting horseradish in pots or in a cordoned-off area of the garden. Frequent harvesting also limits the spread of the plant but often does not stop it completely. While many see this as a burden, the aggressive spread is ideal for gardeners with an intense appreciation for horseradish – plant it once and you’ll have a lifetime supply. It’s also ideal for beginners due to its rapid growth and ease of care.
Propagation
If you’re looking to grow even more horseradish plants faster than the plant will spread on its own, they are incredibly easy to propagate. In fact, they probably sit high on the list of easiest garden plants to propagate, as the tiniest piece of root will quickly grow into a full plant. These plants are commonly propagated by division. This method is also useful if your plant begins spreading and becomes too densely packed. Simply divide the plants and place in pots or in another area of your garden to continue growing.
Propagating by Division
It is possible to split the root of a horseradish plant to propagate it.
To propagate horseradish, first begin by preparing your soil. As a root vegetable, it’s important that the site is completely free of weeds and is amended with plenty of organic matter for healthy growth. If growing in containers, ensure the medium is light (preferably mixed with a peat alternative or perlite) to prevent waterlogging and rotting of the roots. Lift the plant out of the soil gently using a fork. Ensure you don’t damage any parts of the root or break any off, as any roots left in the soil will likely regrow. Once the plant is lifted, you can either cut at the crown of the plant, or at the root, depending on the growing season. In colder areas, crown cuttings will help the plant establish quicker before the leaves die back. Once the roots are cleaned and dried, split the plant vertically with each section containing a healthy amount of leaves. These cuttings can then be planted deeply back into the soil as they are. In warmer areas, root cuttings are a viable option and will likely yield more plants. This can be done when the leaves of the plant die back around autumn. Simply cut the roots into 6-inch pieces and plant each piece around 1-2 feet apart. Come spring, leaves should emerge from the planting spot, indicating the roots have been established.
Planting
The most important factor in planting horseradish is quality soil.
Planting horseradish could be as easy as throwing the root in the ground and letting it grow. However, in order to keep your plants as healthy and productive as possible, there are a few factors to consider. The first is soil. As horseradish is a root vegetable, soil quality is incredibly important. Ensure you loosen the soil at least 10 inches down to help root growth and amend with plenty of compost. Remove any weeds or materials that could hinder the root’s prolific growth. Once the ground is prepared, the roots can be planted 1-2 feet apart. Ensure you place the root in the ground the right way up – the roots won’t grow upside down. If you’ve purchased your horseradish set from a nursery, the bottom end is usually cut at an angle, with the top end square. It’s best to plant at a slight angle (45°) to allow the roots to grow without interfering with the neighboring plants. Ensure these roots are all placed in the same direction for easy harvesting. Once placed in the planting hole, cover with 2 inches of soil and gently press to secure in place. Follow the same procedure when planting in containers. Ensure your container is deep enough to accommodate the long roots without crowding, at least 25 inches deep.
How to Grow
Horseradish is so tolerant of such a wide range of conditions that it is almost impossible to get growing wrong. When gardeners say “plant it and forget it”, they really mean it. In fact, you probably will forget about it when the leaves die back in winter, only to be welcomed by masses of lush green foliage in spring. If you want the best roots possible, there are a few conditions to consider, but they don’t need to be followed too closely – horseradish will grow just about anywhere.
Light
Horseradish thrives where it can receive full sun, at least six hours.
Horseradish grows best in areas with full sun. This greatly improves root growth, making the roots you eventually harvest bigger and tastier. They can also grow well in areas with partial shade, but the roots will not grow as well with less sunlight. If you’re planting several horseradish plants, shade is not a problem, but if you’ve only got one or two and want a significant harvest, focus on full sun. Those lacking the right planting spot can always plant in containers. This is recommended anyway to avoid the intense spread of horseradish through the rest of your garden, but it also allows you to modify the light conditions throughout the day, ensuring your horseradish remains in a full sun spot while accounting for the movement of the sun.
Water
Horseradish needs just the right amount of water to keep the roots from getting to hard without rotting. Watering often when the plants are young helps speed up growth and keep the roots healthy. But, once established, horseradish is considered relatively drought tolerant and isn’t a high water consumer. If the soil remains dry for too long, the roots may become woody and unpleasant to eat. This won’t damage the plant in the long term, as new growth will appear from these woody roots, but it will ruin your harvest. Ensure you water just as the soil dries out to keep the roots and leaves in the best possible shape. Avoid overwatering at all costs. Excess water in the soil can lead to root rot and encourage a wide range of diseases that will permanently damage your plants. Rather underwater and stay on the safe side than overwater.
Soil
It can’t be said enough: the soil is the most important factor if you want to grow horseradish in your garden. Horseradish will grow in a wide range of soils, even those considered poor quality. However, it is unlikely to grow well under these conditions. For thick, healthy roots and a long-lasting plant, soil is the most important condition to consider. The soil should be incredibly loose and well-draining. This provides the least resistance, allowing the roots to travel downwards without trouble, and prevents waterlogging that ultimately leads to root rot. The pH is not a major factor impacting growth, but these plants do prefer a slightly acidic to neutral soil rather than an alkaline soil. Amend the soil with plenty of compost before planting and often afterward to promote soil health. The good organisms and nutrients from the compost will go straight to improving the roots, bettering your harvest overall.
Climate and Temperature
Cooler climates are favored by horseradish, and frost should not kill it.
These plants prefer temperatures on the cool side. Cold soil over winter actually improves the flavor of the roots, so tough winters are not a problem for this plant. Frost is also not a problem – it will kill the leaves, but the roots will remain alive and well in the soil below, ready to bounce back next season. Horseradish grows best in USDA Zones 4-7 or 8. It may occasionally grow well in Zones 3 or 9, with some conditions adjusted for optimal growth. In general, cool moderate climates are best, but this plant is incredibly adaptable to a wide range of conditions.
Fertilizer
If planted in nutrient-dense soil, your horseradish plant should have no need for fertilizer. Fertilizing horseradish is not a necessity as these plants grow relatively well without any added nutrients when planted in the right soil. Regular composting, before planting and throughout growth, will improve soil health enough to keep your horseradish roots growing rapidly. Those wanting to boost their harvest and improve overall growth, or those will poor soil nutrients, can apply a balanced vegetable fertilizer at the beginning of spring. Vigorous leaf growth is a good sign as the plant focuses its attention on the leaves in spring and summer, switching to the storage of starches in the roots over autumn as the leaves die back.
Maintenance
It is highly important to maintain horseradish so it does not take over your entire garden. Horseradish requires little to no maintenance, making it ideal for beginners or the occasionally lazy gardener (guilty as charged). Regular weeding is encouraged during the early stages of growth for good root health, but not much else is needed to keep these plants in great shape. Rather than maintenance, your most important task will likely be control. Keeping these plants contained to the area you planted them in is not an easy task. Monitoring their spread and harvesting or dividing plants when necessary is just about the only maintenance you’ll need to manage.
Harvesting
You should have plenty of horseradish root to harvest in the spring or fall.
Horseradish needs time to establish; at least one season, but preferably two. Harvest when needed, ideally in spring or autumn for the best flavor, by loosening the soil with a gardening fork. Follow the direction of the root, loosening the soil as you go, to make it easier to remove. If you don’t want any horseradish to grow back next season, make sure you remove the entire root and any smaller roots that come off during removal. Once pulled, scrub the roots clean and leave them to dry. They can then be stored in the fridge for several months in a plastic bag or container. You likely won’t have any problems with harvesting, but rather the problem of having too much to harvest, and more than you know what to do with.