Wasabi: A Guide to Cultivating the “Hardest” Plant in the World

Is Wasabi Really the Hardest Plant to Grow?

Wasabi (Eutrema japonica) is often labeled the most difficult plant to grow commercially. Articles like those from the BBC repeat the myth, and many gardeners shy away from even trying. But here’s the truth: wasabi isn’t hard to grow—it’s just misunderstood.

This blog breaks down exactly how to cultivate wasabi in hydroponics or soil, drawing on firsthand experience growing thousands of plants.

What Kind of Plant Is Wasabi?

Wasabi belongs to the Brassica family, just like cabbage, broccoli, and kale. This means it shares similar nutritional needs, particularly:

• Calcium
• Sulphur

Adding extra calcium and sulfur will enhance wasabi’s distinctive fiery flavour—more intense than horseradish and mustard combined.

Top Growing Conditions for Wasabi

✅ Shade & Temperature:

• Needs shade during extreme summer heat.
• Will tolerate moderate heat and light but can’t handle direct sun or drying out.

✅ Moisture:

• Wasabi is a riparian plant, meaning it naturally grows near flowing streams, not stagnant water.
• Soil or media must stay consistently moist, but not waterlogged.
• Oxygenated moisture is key—never let it dry out, and never let it sit in swampy conditions.

✅ Best Growing Media:

• Use coco coir mixed with grit or small stones for drainage and root aeration.
• Avoid perlite—wasabi appears sensitive to aluminium found in perlite.

Hydroponic Setup Tips

Wasabi grows extremely well in controlled hydroponic environments with the right setup:

• Use rockwool (commonly used in New Zealand).
• Set up Ebb and Flow or sub-irrigated beds like “Ewhurst Beds”—self-watering systems developed in Hampshire, UK.
• Consider nutrient solutions like Liquid Gold (UK) or Gold Leaf (USA).

Propagation: Forget Seeds, Use Division

Wasabi seeds are tiny and difficult to germinate. The best propagation method?

• Use division with a sharp scalpel.
• Ensure each new plant includes a portion of the apical meristem and leaf tissue.
• In time, one plant can become hundreds.

Common Wasabi Pests and Diseases

Like other brassicas, wasabi is prone to:

• Cabbage white butterflies
• Flea beetles

✅ Pro tip: Grow in greenhouses or polytunnels to reduce pest damage.

When and What to Harvest

Wasabi is grown primarily for its swollen underground rhizome, which takes 1.5 to 2 years to mature. However, you can also harvest:

• Leaves (less valuable, but edible)
• Flowers (bolt once a year, edible, intense flavor)

Note: 15–20% of plant resources go toward flowering, which can’t be avoided.

True Wasabi vs. Supermarket Wasabi

Most store-bought “wasabi” is actually:

• Horseradish
• Green food coloring
• Sometimes blended with wasabi leaf or root powder

Real wasabi root must be freshly grated using a traditional Japanese grater (or a standard one will do—avoid shark skin graters). Its spicy flavor peaks after 2 minutes and fades after 20 minutes, making it ideal for gourmet restaurant use but not for mass production.

✅ Quick Recap: How to Grow Wasabi Successfully

Final Thoughts: Wasabi Isn’t Hard—It’s Just Different

Wasabi has a reputation for being difficult, but if you understand its natural environment and provide:

• Constant moisture (not waterlogging)
• Proper nutrition
• The right grow medium and temperature range

…then you can absolutely grow it successfully.

If you’ve tried growing wasabi or want to, drop a comment and share your experience

Article by Dr Russell Sharp

If you would like to keep up to date with subjects just like this, you can listen to both our podcasts! Links can be found bellow:

Hydroponics Daily Podcast: https://open.spotify.com/show/207T7p7fw9sPjINfSjVXW2

Cereal Killers Podcast: https://t.co/eSEbBkTVHl