Wasabi (Eutrema japonicum)
1 sources cited · Verified
The short answer
- Site
- 0+ hours of sun, soil pH 5.5–8
- Biggest risk
- Phytophthora blight
Wasabis (Eutrema japonicum) — herbaceous perennial.
Unlike an annual crop, the work here is front-loaded into establishment: get the planting and the site right and the same plants crop for several seasons.
Core growing advice on this page is checked against named horticultural and university-extension sources — see References.
Soil & Growing Conditions
Water: moist, good drainage, tolerates occasional flooding (NC State)
Soil pH range
Span reflects genuine variation between the cited authorities, not a single agreed figure.
Growth Stages
| Stage | BBCH | Notes |
|---|---|---|
| Seed preparation and sowing | 0 | Sow late fall to early winter; needs about two months of cold before sprouting. Soak seed overnight in distilled water first; plant 2in deep, one seed per hole, rows 2in apart (NC State). |
| Establishment | 3 | Dappled sunlight to deep shade; organic, loose, moist, well-drained soil at 46-70F; container growing needs a shallow water pan (NC State). |
| Rhizome development | 4 | Rhizome develops slowly, taking up to three years to reach harvest size of 1 inch diameter (NC State). |
| Harvest | 8 | Pull the whole plant once the rhizome reaches 1 inch diameter; grate within 30 minutes of harvest for best flavour (NC State). |
Quick Facts
| Factor | Value |
|---|---|
| Soil pH | 5.5 - 8 |
| Sunlight | 0-0 hours direct sun |
| Soil texture | clay, loam or sand; organic, loose, crumbly (NC State) |
| Drainage | well-drained |
| Lifecycle | herbaceous perennial |
| Edible parts | rhizome, leaves, flowers |
At a Glance
Harvest & Storage
When to pick: Rhizomes take up to three years to reach a harvestable size of 1 inch in diameter. Harvest by pulling the whole plant; best flavour comes from grating the cleaned root within 30 minutes of harvest, though it can be kept refrigerated for a month (NC State).
Diseases
Pests
Wasabi, Seedling to Grated Rhizome
References
-
Hardiness USDA zones 7a-10b. Light: dappled sunlight (shade through upper canopy) to deep shade (less than 2 hours direct sun). Soil: clay, loam or sand; pH acid, neutral or alkaline; good drainage with moist conditions, tolerates occasional flooding and wet soils; plant in organic, loose, crumbly soil, add coarse sand to improve drainage. Optimal growing temperature 46-70F; native to mountainous riverbank environments similar to fern habitat. Best sown late fall to early winter, needing about two months of cold before sprouting; soak seed in distilled water overnight to soften the coat and speed germination; plant 2 inches deep, rows 2 inches apart, one seed per hole. Container growing: containers at least 10-12 inches deep and wide, set in a shallow water pan. Propagate by division, seed, or plantlets. Rhizomes take up to three years to reach harvest size of 1 inch diameter; harvest by pulling the whole plant; best flavour comes from grating cleaned roots within 30 minutes of harvest, though roots keep refrigerated for a month. PESTS: aphids, alfalfa looper larvae, crane fly larvae, slugs, snails. DISEASES: leaf spot, root rot, rhizome rot; susceptible to phytophthora blight. Medium maintenance; slow-release 12-12-12 fertiliser adequate for 3-4 months; keep well-watered but not standing in water; prune wilted, damaged or dead leaves to deter pests and disease.
1 independent sources are cited for this crop. Where they disagree - soil pH is the clearest case - every figure is preserved rather than averaged into false precision.
Frequently Asked Questions
What soil pH do wasabis need?
A pH of about 5.5–8. That span reflects genuine variation between the authorities we cite rather than a single agreed figure — the References section lists each source's exact range.
What problems affect wasabis?
Our data links 1 disease and 3 pests to this crop. See the sections above for each one and how to manage it.
Plan next season before the problems start
Almost everything on this page resolves to your own frost dates rather than the calendar — the last spring frost moves by roughly two months between zone 3 and zone 10. The USA Garden Planner works from your zone so the timing is already decided before the season starts.
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Last verified 2026-08-29
Where To Go From Here
Take this crop from reading into a written plan for your own beds.
Plan the next step
Use the printable SoilCommander planner for your region to turn this guide into sowing dates, bed layouts and weekly garden tasks.