Scientific Name: Amoracia rusticana
Family: Brassicaceae (the Mustard and Broccoli family)
Horseradish is a fairly well known condiment with its spicy, sinus-clearing, pungent flavor. This plant, with its famous roots, also has edible leaves, confuses garden pests with its scent, and can be grown in almost any location. A perfect plant for the Edible Food Forest.
Likely originating from southeastern Europe and western Asia, horseradish was popular with the ancient Greeks, Egyptians, and Romans. It was popular during medieval times in Europe and Britain as a food and medicine. European colonists brought horseradish to North America. Today it is used all over the world.
- Whole Horseradish roots have almost no aroma, but once the root’s cells are ruptured (from cutting or grating), the enzymes released will convert the naturally produced root compound sinigrin into the highly aromatic allyl isothiocyanate (a.k.a. mustard oil).
- The English name “Horseradish” likely came about through ignorance. The German name for this plant is meerrettich (meer = sea; rettich = radish). At some point this was mistakenly called mahrrettich (mahr = mare (female horse); rettich = radish). It is not a far leap for someone to mistakenly translate the mare radish to horse radish.
USING THIS PLANT
- Roots – typically grated raw and mixed with vinegar; may be sliced and cooked like other tubers or carrots/parsnips; can be dried, then ground to a powder, but it is not as strongly flavored as fresh.
- Leaves – “Horseradish Greens” are edible, and reportedly have a horseradish flavor. I’ve never tried them, but I think they could be used raw in small amounts in a mixed green salad or used cooked as a spinach replacement. Also used in pickling cucumbers to keep the cucumbers crunchy (as are grape leaves).
General insect (especially bees) pollen plant
- Aromatic Pest Confusor
- Pioneer Species
Yield: Variable, but roots can grow to over 20 inches (50 cm) long and 2 inches (5 cm) thick.
- Leaves – smaller, new growth ideal for salads; older growth best cooked.
- Roots – As desired. The plant grows the most during late Summer and early Autumn, so waiting until just before the ground freezes (depending on your location) will give you the maximum yield. Alternatively, you can harvest in the Spring. Dig a hole or trench 12-24 inches (30-60 cm) deep along the plant, then from the opposite side dig the roots back to the hole. Grab the base of the greens and pull the roots out laterally toward the hole. Use the largest taproots for processing, and use the smaller roots for Spring planting stock if harvested in Autumn or immediately if harvested in Spring. NOTE – Horseradish roots older than 2 years can get stringy and woody. In a Forest Garden, we can harvest in the Spring and replant smaller roots immediately, or we can leave a patch of horseradish growing and harvest from the outer ring or just toss the woody roots in the compost bin or in the forest to compost in place.
- Leaves – use as any other green
- Roots – peel the brown “skin” off the root; roughly chop; add to a food processor or blender with a little bit of water or you can use a simple vegetable grater or food grinder (whatever way you choose, do so where you have a breeze to blow the fumes away!); add a tablespoon of white vinegar (white wine or distilled vinegar) and a pinch of salt for every 10 inches (25 cm) of root (or 2-3 tablespoons vinegar and ¼ – ½ teaspoon salt per each 1 cup grated horseradish). Vinegar stops the enzymes from converting the sinigrin to the hot mustard oil, so add vinegar immediately after grating for mild and wait for about 3 minutes for hot horseradish.
- Leaves – use immediately
- Roots – Use immediately for best flavor. Can be stored in dry sand for a few months (a cooler location will keep for longer – ideally under 40 F (4 C) but above freezing); this dry sand storage is a great place to put Spring planting stock. If wrapped in plastic and placed in the coldest part of the refrigerator, it may stay good for a few months. Light will turn the roots green. Processed, refrigerated horseradish will last about a month.
DESIGNING WITH THIS PLANT
USDA Hardiness Zone: 2-10 (although some sources are more conservative at 5-8)
AHS Heat Zone: 12-1
Chill Requirement: Not likely, but not good information available
Plant Type: Large Herbaceous Plant
Leaf Type: Deciduous
Forest Garden Use: Underground Layer, Herbaceous Layer
Cultivars/Varieties: There are only a few named cultivars.
Flowering: Late Spring to early Summer (May-June)
Life Span: No good information available as we typically harvest roots of plants less than 2 years old.
PHYSICAL CHARACTERISTICS OF THIS PLANT
Size: 3 feet (0.9 meters) tall and as wide as you allow it to grow
Roots: Large taproots
Growth Rate: Fast
Light: Prefers full sun
Shade: Tolerates moderate shade
Moisture: Dry to moist soils, but prefers soil a bit more damp
pH: 5.1-8.5 (tolerates a wide range of soil conditions)
Special Considerations for Growing:
Reported to inhibit brown rot if planted under apple trees.
Typically from root cuttings or divisions in Spring; ideally at least 8 inches (20 cm) in length. Any root will likely grow to a new plant. Seed is not typically produced in plants grown in modern cultivation, but if a patch is allowed to mature, then seed will likely form. Seed is best sown in place.
- Root Rot can develop – just replant strong roots and compost the rest.
- Some insects can cause extensive leaf damage in traditional gardens; this doesn’t affect the roots much and should be less of a problem in a Forest Garden.
- A thorough digging and dividing of the roots every 3-4 years will keep a patch healthy, growing strong, and productive.
Poisonous – Reportedly, if one consumes a large amount of fresh roots the strong, volatile oils can be poisonous. This is not well researched, nor do I think people typically consume large amounts at any one time!
- Spreading Habit – some sources state this plant can become invasive by spreading too fast, and other sources state that this rarely occurs.