Not Many Brits Know How to Grow Wasabi. But It Is A Surprising Plant That Loves Shade & Moisture. And Its Flavour Is Superb.
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Not many gardeners grow wasabi in the UK. But if you are a gardener looking for a challenge or to grow something a little different, Wasabi japonica is ideal.
The first thing that surprises most gardeners is that wasabi is a brassica. It is related to cabbages, caulis and sprouts. But is more akin to horseradish and mustard. Wasabi is a Japanese favourite that loves cooler, cloudier, even wetter summers, you can see where I’m going with this!
Wasabi Origins
Wasabi, aka Japanese horseradish, is native to Japan, the Korean Peninsula and Far Eastern Russia. In Japan wasabi has been recorded as long ago as the 8th century AD. In the UK it has only become widely known since the 1980s, from the era when sushi became popular.
Wasabi as An Ingredient
It’s not just eaten with Sushi, it can be eaten with western dishes as well. It is often regarded a great substitute for horseradish with roast beef. And I like it grated into salads. But it is also used as a flavouring with nuts, beans, sour beans etc. The simplest way to do this is a a dried powder. That’s certainly how manufactured wasabi flavoured products are often made. But in the kitchen at home we tend to use it as a paste, freshly made with a little veg oil or alone.
Some people suggest eating the leaves. Others suggest they easily upset stomachs!
Cultivating Wasabi Root In the UK
Wasabi thrives in shady spots, away from direct sunlight, and prefers a cool, humid environment with temperatures between 8-20°C. If you can provide these conditions, you’ll be rewarded with aromatic rhizomes that, when grated, add that signature sweet, peppery kick to sushi and other dishes. But don’t stop there—the leaves and flowers are also edible, offering a milder, fresher flavour that’s perfect for salads or tempura. In early spring, wasabi grows clusters of fragrant white flowers, adding yet another edible delight to your garden.
Where to Grow Wasabi
Wasabi is a versatile plant that can be grown in pots or directly in the ground. It’s perfect for shady, humid spots, like the edge of a pond or under a tree. Just make sure the soil is rich in organic matter, well-drained, and kept consistently moist. While it’s a hardy plant, tolerating temperatures as low as -5°C, usually it will shed its leaves in winter. Interestingly, I keep mine in a small pot sat in a tray of shallow water and it doesn’t lose it’s leaves. If you’re in a colder part of the UK, it might be wise to protect your plants with mulch or horticultural fleece during harsh frosts or snow.
Caring for Wasabi
Soil: Moderately fertile, moist, and well-drained. Add plenty of organic matter before planting.
Position: Full shade or light shade—avoid direct sunlight and excessive heat.
Watering: Keep the soil consistently moist, especially during dry spells.
Harvesting: Rhizomes can be harvested from April to October. Leaves and flowers can be picked as needed.
Winter Care: In colder regions, mulch around the base of the plant or use horticultural fleece to protect it from prolonged frost.
Key Features
Height and Spread: Grows to about 0.4m tall and wide.
Flowering Period: Produces fragrant white flowers in late winter to early spring.
Growth Rate: Fast-growing, so you won’t have to wait long to enjoy your harvest.
Hardiness: Fully hardy in all but extreme conditions, making it a resilient choice for UK gardens.
Propagating Wasabi Plants
The root (or more correctly the rhizome) of wasabi plants can be propagated when it is two or more years old. Even easier is to remove offshoots and grow them on. Finally it is possible to grow the plant from seed. But it is an unreliable method and takes longer.
In Japan they use tissue culture to produce cloned plants of the very best stock.
Wasabi Rhizome Propagation: The Video
Here’s an American based video on rhizome propagation of wasabi. I often advise caution when watching overseas gardening videos as conditions are very different. But in this case the advice is sound.
UK Wasabi Culture Conclusion
Learning How to Grow Wasabi Roots might seem a bit daunting at first, but with the right conditions, it’s surprisingly straightforward. Plus, the reward of harvesting your own fresh wasabi—whether for sushi, salads, or tempura—is well worth the effort. So why not give it a go and add a touch of Japanese or Korean flair to your garden? Happy growing! 🌱
