Wasabi
Eutrema japonicum
Also called Japanese horseradish and Wasabia japonica
Garden plant · Herbs, veg & fruitCOLD RUNNING WATER AND DEEP SHADE, and almost nobody gets it right — it wants 8–20°C all year, constant moisture and no sun at all. Two years to a harvest, and the green paste in shops is usually horseradish and mustard, not this.
Care at a glance
- Ease
- Very hard
- Water
- Every dayKeep it moist — water at the first hint of dryness — don't wait for a dry pot.
- Light
- Full shade
- Feed
- Every 45 days
- Humidity
- High
- Hardiness
- Hardy — a cold winter RHS H5, to -15°C
- Size
- 0.5 m tall · 0.5 m across
- Lifecycle
- Perennial
- Origin
- Japan
Is it safe for pets and people?
No animal-poison authority lists this plant either way.
Nobody has checked this one against a source for us yet, so treat it as unknown rather than safe.
Neither authority names Eutrema, nor the older name Wasabia. That is an absence and not a clean bill.
Checked against ASPCA and RHS on 2026-09-22. Where a source says nothing, we say nothing.
A guide, not veterinary or medical advice. If a pet or a person has eaten a plant and you are worried, call your vet or doctor now — don’t wait for signs to appear. Spotted a mistake? Tell us.
First signs of trouble
- Leaf edges browning and the whole plant collapsing in an afternoon. It wants FULL shade and 8–20°C — an hour of direct summer sun is enough to finish one.Scorched in sun · disorder
- The rhizome soft and sour at the base, in a pot standing in a tray. It wants water MOVING past it, not water sitting round it — in the wild it grows in a stream bed.Rot in still water · disease