Horseradish is featured in a Pompeii mural, in Pliny the Elder's Natural History, and in Greek mythology, when Apollo was told that the vegetable was worth its weight in gold. Renowned Greeks such as Cato and Dioscorides also mentioned the plant, and it was widely used as a medicine throughout the Middle Ages.
Once introduced into North America, indigenous tribes used horseradish to treat everything from the common cold to gland issues and scurvy, and presidents George Washington and Thomas Jefferson both cataloged it in their gardens.
While horseradish is an outdoor, cold-hardy plant, it can also be grown in indoor containers. Aim for moist, fertile soil with a slightly acidic to neutral pH level, and get started in early spring. Horseradish has a lengthy growing season, so you'll either be harvesting in the fall or the following spring after the freeze.
Place roots vertically into the soil at a 45° angle, add compost, and cover with topsoil. When planting indoors, select a deep, 24 to 36 inch pot with drainage holes so that roots have room to spread out.
Plants reach an average two-foot height, but horseradish roots have significant space requirements. The long, fleshy taproots penetrate deep, crawling up to 10 feet underground. This creates a web of secondary roots that extend even further, for a root system that's several feet long.
Though space is necessary, this is why many home gardeners choose a container system; they don't have to worry about digging out roots post-harvest and can manage the growth.
Horseradish is a hardy plant, but the better the growing conditions, the better the yields, and the stronger, more flavorful the taste come harvest time. While horseradish still grows in partial sunlight, you'll experience a less successful crop. Ensure that plants get direct sunlight throughout their growth cycle for optimum results.
Always adaptable, horseradish can grow successfully even during a drought. This impacts flavor, however, as the roots become woody and weak, with taste quickly seeping out. Water your plants regularly, especially if rain is scarce. Aim for one to two inches a week, but avoid overwatering, which gives the roots a bitter taste.
Cabbageworms and flea beetles prey on horseradish, biting large holes into leaves. On seedlings, this damage can quickly spread and destroy the entire crop, so keep an eye out. Freshly bitten leaves will often have a "lacy" look before the damage gets deeper, giving you time to react.
To eliminate pests, dust plants with flea-repelling talcum powder, use insecticides during the earliest part of their growth cycle, and bring out sticky traps to capture worms and fleas.
Pests can easily spread diseases as they move between leaves, so infection rapidly moves from plant to plant. Blight is the most common, resulting in severe yellowing, browning, spotting, and sometimes death. Once identified, remove infected leaves and thoroughly mulch the plant base to stop the spread.
Wilt affects the vascular system, so it can destroy your entire harvest. Save affected plants by removing them from the soil, washing the roots, and trimming the affected areas away.
Harvesting is the best way to prevent disease buildup and spread. Harvest every spring and fall, rotating the beds each time.
Horseradish plants are relatively low-maintenance, but they benefit from high-quality fertilizer that's low in nitrogen and high in phosphorus. Since they can thrive during rough winter conditions, this boosts soil quality for improved growth while helping your garden maintain a level pH all season. Weeding also encourages strong growth while reducing the risk for pests and disease.
Perfect for propagating, new plants can spring to life via rootlets from the main taproot. Since established plants grow such an extensive root system, ensure that the rootlets gathered are from this source only; secondary roots won't do the trick. Slice the side root into six- to eight-inch long sections and bury these cuttings with the root well-covered and well-watered. For best results outdoors, plant these newcomers in the soil about six weeks before the last frost.
Most gardeners prefer the taste of one season's horseradish over the other: either late fall or early spring. Give both a try to see which variety you enjoy best; come harvest time, simply pull out the garden shovel, dig up the roots, and you're ready to prepare your side dish. Note that flavor becomes more pungent the finer plants are grated or ground, so you can play an even further role in its taste.
Diners enjoy a wide range of benefits from horseradish, which comes to harvest brimming with nutrients. The root vegetable has 20 times more calcium than a potato, and its vitamin C content far exceeds that of oranges, helping to boost the immune system and protect cells from free radical damage.
Horseradish root is rich in vitamins and minerals, including iron to aid growth and development, potassium to regulate fluid balance and muscle contractions, and magnesium, which supports muscle and nerve function.