Gardeners and chefs looking for a unique addition to their herb gardens should consider horseradish (Armoracia rusticana). The spicy root of this European native is the part we grind up and use on roast beef sandwiches, but the aboveground part has appeal, too. Horseradish’s large, broad green leaves look almost tropical. Think rhubarb leaves but with an oval shape. The plant is extremely tough in the face of heat, cold, drought, and neglect. Horseradish will happily settle in any sunny corner of your garden, but beware: You’ll have a hard time evicting it if you ever change your mind. Each tiny piece of horseradish root that stays in the ground can sprout a whole new plant.
Common name: Horseradish
Botanical name: Armoracia rusticana
Plant type: Perennial
Zones: 3 to 10
Height: 2 to 3 feet
• Sun: Full sun
• Soil: Average
• Moisture: Medium
• Mulch: Mulch to preserve moisture in the soil.
• Pruning: None needed
• Fertilizer: None needed
• By division
Pests and diseases
• Vulnerable to downy mildew, powdery mildew, root rot, and leaf spots.
• Unless you’re planning to start a small farm, you don’t need more than one or two horseradish plants. Each fall or spring, dig up the entire root system. Harvest the biggest roots for kitchen use and replant a few of the small roots—these will become your next harvest.
• Horseradish isn’t a rampant colonizer, but it will spread over time. It is also incredibly persistent. New plants will sprout from tiny pieces of overlooked root. You’ll have less trouble if you dedicate one spot to this vigorous herb and don’t try to move it.
• Be sure to give horseradish plenty of room. This is not a small plant, and its big broad leaves will shade out smaller plants if they’re too close.
• The big leaves have a pleasant, faintly spicy scent.
All in the family
• Cabbage, broccoli, cauliflower, collards, and Brussel sprouts are also in the Brassicaceae family.
• Most of the commercial horseradish grown in the United States comes from southwestern Illinois. Collinsville, a town in this region, holds the International Horseradish Festival every year.
(Text by Elizabeth Noll, photo of Armoracia rusticana courtesy of the Kemper Center for Home Gardening at the Missouri Botanical Garden)