Here’s how I grow my lush green Wasabi plants:
Lots of people think Wasabi is difficult to grow, but it’s fairly easy if you just give the plant what it needs.
Wasabi likes a shaded position. If they get harsh sunlight, they’ll droop. Wasabi doesn’t like our hot summers so ensure they’re shaded.
I grow mine in shade houses and in the garden. Wasabi doesn’t like significant temperature fluctuations, so try and keep its environment fairly consistent. Wasabi plants like the cool weather.
Although Wasabi grows wild along stream beds in Japan, it is not an aquatic plant. The soil must be kept moist / wet but free draining (don’t sit them in water).
I use a rich, healthy potting mix for my potted plants and compost-rich soil for the plants in the ground. The pH of the soil should be around 6-7.
Because Wasabi must be kept moist, the plant can be susceptible to disease and mould. Try and use a drip irrigation system instead or watering from above with a hose. Watering from above can lead to root rot or fungus growth and this can quickly spread to other plants. Check your plants regularly for root rot (too much water) or wilting (not enough water) and adjust your watering levels accordingly.
I grow ‘Mazuma’ which is a slower growing variety. It can take up to three years to harvest the rhizome, but most plants normally take about two years before the rhizome is ready to harvest. During this time, the plant will grow about 60cm high and 60cm wide then it’ll start putting its efforts into growing the carrot like rhizome (the green knobby part which rises up just above the soil line). The rhizome is what’s ground up to make Wasabi paste.
To harvest the rhizome, pull the whole plant up. You’ll see off-shoots growing from the sides, so carefully break them off and replant them and continue the process again.
But you don’t need to wait so long before you can start eating the Wasabi plant as the leaves and stems are also edible and they’re great for adding some heat to salads or you can juice them and add them to drinks. They can also be used in cooking. When you harvest the leaves, ensure you leave the little leaves sprouting from the top centre of the plant.
I always leave some Wasabi plants in the ground to go to seed. When they sprout, I ensure they’re well spaced for if you leave them in clumps, many will wilt and die. I just lift them with a spoon and replant them.
So don’t let rumours of Wasabi being finicky or hard to grow deter you from growing your own beautiful plants. Fresh Wasabi is a great treat and it’s such a rewarding plant to grow.
