Growing
Patience, shade and cold water
Wasabi is famously difficult to grow — which is exactly why real wasabi is so rare and prized. Here's how farmers do it, and how you can try.
Two methods
Sawa and oka
沢わさび Sawa
Stream-grown in terraced gravel beds fed by spring water. Produces the largest, most aromatic rhizomes. The traditional Shizuoka method, recognized as a Globally Important Agricultural Heritage System.
畑わさび Oka
Field-grown in moist, shaded soil, often under forest trees. Easier and cheaper, with smaller rhizomes — mostly grown for leaves and stems used in processed products.
Conditions
What wasabi needs
- Temperature
- 8–20 °C, ideally 10–15 °C. Above 27 °C the plant suffers.
- Shade
- 50–70% shade. Direct sun scorches the leaves.
- Water
- Cool, oxygen-rich, constantly moving water for stream beds; evenly moist soil for field growing.
- Humidity
- High — misty valleys are the natural home of wasabi.
- Soil pH
- Slightly acidic to neutral, 6.0–7.0, rich and free-draining.
Step by step
From plantlet to harvest
- 01
Start plants
Grow from seed (slow, sown in autumn) or, more reliably, from plantlets or offsets of a mature plant.
- 02
Prepare beds
Stream beds use layered gravel and sand with flowing water. Soil beds need loose, compost-rich earth under shade cloth.
- 03
Plant out
Space plants about 30 cm apart, rhizome crown just above the surface.
- 04
Tend
Remove yellow leaves, keep roots cool, clear slugs and aphids. Pinch flowers in the first year to build the rhizome.
- 05
Wait
Rhizomes need 18–24 months to reach 10–20 cm. Leaves and stems can be harvested much earlier.
- 06
Harvest
Lift the whole plant, trim roots and leaves, and replant the side shoots for the next crop.
Problems
Common troubles
- Wilting in summer — too hot or sunny. Add shade, mist the leaves, move pots somewhere cooler.
- Soft rot — standing water or poor drainage. Wasabi wants moving, not stagnant, water.
- Slugs and aphids — check leaves often; use beer traps and a soapy water spray.
- Yellow leaves — natural for old leaves; remove them. Many at once may mean nutrient shortage.
At home
Growing wasabi in a pot
- • Use a deep pot (30 cm+) with a gritty, compost-rich mix and good drainage.
- • Place it in full shade on a north-facing side, or under trees.
- • Water with cool water often — even daily in summer — and never let it dry out.
- • Protect from frost below −5 °C and heat above 27 °C.
- • Harvest leaves after a few months; enjoy the rhizome after about two years.