The horseradish plant (Armoracia rusticana) is a hardy perennial herb known for its thick, fleshy taproot, which delivers its signature pungent heat. While typically propagated from specialized root cuttings, the root available in the produce section of a grocery store is entirely viable for starting your own patch. Growing from a store-bought root simply requires careful selection and preparation to encourage the root to transition from a harvested vegetable back into a productive plant.
Selecting and Preparing Store-Bought Roots
The first step involves choosing a healthy root that shows potential for renewed growth. Look for roots that are firm to the touch, without any shriveling, soft spots, or mold. The root’s color should be a consistent creamy white beneath the skin, suggesting freshness.
Once selected, the root must be cut into appropriate pieces, ideally pencil-sized sections that are about six to eight inches long. This size provides enough stored energy to support initial leaf growth. Identify the top end, which is usually thicker and may have small buds where the leaves were attached, and the thinner bottom end.
A common technique involves making a straight cut across the top end and an angled cut across the bottom end, a simple method to remember the correct planting orientation. If the root has been treated with a food-grade wax, gently scrub or peel the skin where new roots and shoots will emerge to facilitate growth. Allowing the cut ends to air-dry for a day or two helps the wounds callous over, which can reduce the risk of rot once planted.
Preparing the Site and Planting Technique
Horseradish thrives in a location that receives full sun, though it can tolerate partial shade. The soil must be deep, loose, and well-draining, as the taproot can extend deep into the earth, requiring space to develop into a straight, thick root. Prepare the bed by tilling to a depth of at least 10 to 12 inches and incorporating compost or aged manure to create the ideal fertile environment.
To plant the prepared root pieces, dig a shallow trench or individual holes about three to four inches deep. The most successful planting method involves setting the root at a 45-degree angle, ensuring the square-cut (top) end is positioned higher than the angled-cut (bottom) end. The top end of the root should sit about two inches below the soil surface.
Spacing the root cuttings approximately 12 to 18 inches apart provides adequate room for the mature root system to expand. Covering the root with soil and watering immediately helps settle the ground around the cutting, initiating the process of root development. This angled planting encourages the formation of a single, well-developed taproot rather than a tangle of smaller roots.
Routine Care and Managing Spread
Once planted, horseradish is a relatively low-maintenance crop, but it benefits from consistent moisture. Aim to provide about one inch of water per week, ensuring the moisture penetrates the soil deeply without becoming waterlogged. While the plant can tolerate poor soil, a light application of a balanced or low-nitrogen fertilizer during the early growing season can support robust leaf development.
The primary consideration when growing horseradish is its vigorous tendency to spread, which can quickly lead to it overtaking a garden bed. Every small piece of root left in the soil can sprout a new plant, making it difficult to eradicate once established. Containment strategies are essential to manage this spread:
- Planting the root inside a large, bottomless container, such as a five-gallon bucket or drainage tile, and sinking it into the ground to restrict lateral root growth.
- Using a dedicated, isolated bed away from other vegetables.
- Gently scraping away the soil during the growing season to remove smaller lateral shoots that emerge near the crown.
- Focusing the plant’s energy into developing a single, large main root.
Harvesting the Root and Storing the Crop
The best time to harvest horseradish is in late fall or early winter, typically after the first hard frost has caused the foliage to die back. Exposure to cold temperatures triggers the plant to convert starches into sugars, resulting in a concentration of the sulfur-containing compounds responsible for the root’s intense flavor and maximum potency.
To harvest, carefully use a digging fork to loosen the soil around the plant. Digging up the entire root mass is advisable for both harvest and managing the plant’s spread. Separate the main taproot from the leafy crown, and trim away and collect any side roots.
Pencil-sized side roots, approximately six to eight inches long, should be set aside and stored for planting the following spring. The harvested main roots can be stored for several months in a cool, dark location, such as a root cellar. Place them in moist sand, peat moss, or sawdust, or seal them in a plastic bag in the refrigerator to preserve the signature flavor until grating.