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garden
Horseradish
Armoracia rusticana
EdibleMedicinalToxic — Use Caution
Edible PartsLeaves Root Seed
Overview
A powerfully pungent root that has been used as a condiment and medicine since antiquity — Egyptian pharaohs knew it, and it is one of the five bitter herbs of the Jewish Passover seder. Freshly grated horseradish is dramatically more pungent than the jarred version, releasing volatile compounds that clear sinuses on contact. Once planted, it is nearly impossible to eradicate, spreading vigorously from the smallest root fragment.
Growing Conditions
LightFull Sun
MoistureModerate
Hardiness Zones3 — 9
Height0.5m
Spread0.5m
Growth HabitForb/herb
Pollinator Valuehigh
Companion Planting & Soil
Good Companions
Soil pH6 — 7.5
Soil TypeDeep, rich, moist, well-drained soil
Planting Calendar
When to sow, transplant, and harvest by growing zone.
| Zone | Action | Months | Notes |
|---|---|---|---|
| Cold (1-2) | Transplant | Apr — May | Plant root cuttings in early spring; choose site carefully — very hard to eradicate |
| Cold (1-2) | Harvest | Oct — Nov | Dig roots after first hard frost; pungency is strongest in fall |
| Cool (3-4) | Transplant | Mar — Apr | Plant root cuttings 3" deep, angled; perennial to zone 3 |
| Cool (3-4) | Harvest | Oct — Nov | Harvest in late fall after frost; grate immediately — volatile compounds fade fast |
| Moderate (5-7) | Transplant | Feb — Mar | Plant in late winter; grows in any soil; contain to prevent spreading |
| Moderate (5-7) | Harvest | Oct — Dec | Dig roots in fall; replant pencil-thick side roots for next year |
| Moderate (5-7) | Divide | Mar — Apr | Divide in spring; every root piece will grow a new plant |
| Warm (8-9) | Transplant | Jan — Feb | Plant in midwinter; needs some chill for best root development |
| Warm (8-9) | Harvest | Nov — Jan (wraps) | Harvest in late fall/winter after cool weather improves flavor |
| Hot (10+) | Transplant | Nov — Dec | Plant in fall; needs cool period to develop pungent roots |
| Hot (10+) | Harvest | Dec — Feb (wraps) | Harvest during coolest months |
Uses
Culinary
- Freshly grated as a condiment for roast beef and smoked fish
- Mixed into cocktail sauce and Bloody Marys
- Horseradish cream sauce for prime rib
Medicinal
- Powerful sinus-clearing and decongestant action
- Antimicrobial compounds (isothiocyanates) support immune defense
- Traditional poultice for muscle and joint pain
Other Uses
- Companion plant that may deter potato beetles
- Leaves used as a natural preservative in pickling
Safety Notes
Root is extremely pungent; fumes can irritate eyes and nasal passages. Leaves are mildly toxic in large quantities.
