Many people only know wasabi as a hot, green paste that is served with sushi or coated in peanuts for nibbling. The piquant spice naturally comes from Asia. But the plant has now also established itself in European gardens. Planting Eutrema japonicum is not that difficult. If you then take the right care measures, you can soon refine your dishes with spices from your own cultivation.

Interesting facts about wasabi

  • Plant family: cruciferous
  • comes from Japan
  • also known as Japanese horseradish or mountain hollyhock
  • perennial herbaceous plant
  • Leaf shape: large and heart-shaped, long-stalked
  • Flowers: white and filigree
  • Flowering time: spring
  • deciduous in winter
  • extremely intense, very sharp taste


Planting Eutrema japonicum is not only worthwhile because of its rarity and the ideal use for lovers of Japanese cuisine, but also because the plant fills bare, dark corners of the garden. Because the plant feels most comfortable in the shade or semi-shade. Direct sunlight, on the other hand, damages the leaves. Temperatures between 7°C and 20°C are ideal. In addition, the gardener should choose a sheltered location.

Wasabi is suitable for planting outdoors as well as for the bucket on the terrace or balcony. Anyone who cultivates the Asian plant in a greenhouse should cover the glass roof with a tarpaulin to avoid excessive heat development.

Note: If spots appear on the leaves, the wasabi is too sunny.

Simulate the natural climate of home

Nowadays, the Japanese grow their coveted spice on large plantations. However, Eutrema japonicum also grows in the wild. It can be found especially on rocky rivers because it prefers moist soil. At this location, nature provides the best conditions for productive growth. The cold stream water cools the air and warms it up again as soon as the temperature falls below 0°C. The gardener can recreate this phenomenon by pumping groundwater out of the ground with a well. For example, an irrigation system with drip irrigation is ideal.


Wasabi always calls for (not too) damp feet. Although there must be no waterlogging, the soil must never dry out completely. The following soil properties are ideal:

  • wet
  • fumes
  • nutritious
  • locker


To plant Eutrema japonicum directly in the ground, a spot on the bank of a garden pond is ideal. The plant also grows near water in Japan. Depending on the variety, a strong root system forms after some time. The gardener must take this property into account, especially when planting in the tub. The planter must be deep enough to allow the root to spread downwards.

The pot should be at least 30 cm high. Drainage is essential to prevent waterlogging. Commercially available plant pots usually already have a hole in the bottom. The gardener places a piece of pottery over it. He then layers some expanded clay or gravel into the bucket. Only then does the plant substrate follow.

Home grown wasabi?

Although wasabi seeds are also available, the chances of successful sowing are poor for most varieties. It is therefore advisable to purchase early copies. But even with young new plants, a lot of patience is required in order to finally be able to enjoy fresh wasabi. It can take up to three years from planting to the appearance of a tuber.

watering and fertilizing

In order for Eutrema japonicum to feel comfortable, the soil must never dry out completely. The plant has a high water requirement, although it thrives in a shady location. The gardener only reduces the watering during the dormant phase in winter. The right watering behavior requires a little finesse, because waterlogging also damages the roots. It is best for the gardener to let the substrate dry slightly for 2 to 3 days before giving 2 to 3 glasses of water. It is important not only to moisten the upper layer of soil, but also to pour the wasabi deep down.

In Japan, wasabi growers use sprinkler systems. These are also recommended in this country, for example in the greenhouse.

Tip: To keep the soil moist for a long time after watering, we recommend a saucer that catches the water. However, the gardener must also pay attention to waterlogging here.

After Eutrema japonicum wakes up from hibernation in spring, a strong supply of nutrients with flower fertilizer promotes its growth. The once-a-year dose at this time is sufficient.


If the gardener wants to plant wasabi outdoors, overwintering is easily possible with sufficient protection. The leaves are unaffected by temperatures as low as -8°C. Botanists suspect that mustard oils protect the plant from freezing temperatures. For additional frost protection, the gardener layers bark mulch or old leaves to protect the sensitive root system. However, it is more advisable to plant the plant in a bucket that the gardener keeps in the basement or garage during the winter. Winter quarters should be cool and dark. Some daylight is still necessary. That’s why the wasabi is happy about a place by the window. Watering is only sparse during this time, but is still part of species-appropriate care.

Note: Even late spring frosts cannot harm Eutrema japonicum. In this case, only the newly sprouting leaves are affected. However, the majority of the plant withstands the cold without any problems.

To harvest

The gardener uses the root to make the famous wasabi paste. It is ready for harvest at the end of June. However, he can pick the leaves all year round. They taste a little milder and are suitable for salads, for example.

Tip: Homegrown wasabi is a real taste experience and cannot be compared to the ready-made products from the supermarket. In order to save costs, manufacturers often mix their products with additives. In contrast, the natural wasabi unexpectedly even has a slightly sweet note. To intensify the aroma, the gardener should rub the tuber.


Wasabi is a fairly robust plant. Only aphids like to settle on the leaves. The first signs are a sticky coating on the leaves, the so-called honeydew and ants. The former is the excretions of the pests, while ants see the aphids as an important source of food.
With a light infestation, it already helps to spray the plants. For the biological treatment, we use home-made plant brews made from neem or rapeseed oil, horsetail or baking powder and milk. The gardener can also use predators such as lacewings, parasitic wasps or ladybirds from specialist retailers.

Recommended Varieties

  • Daruma: very productive, forms a large root system, convinces with a delicate aroma
  • Mazuma: short, thick tubers, slow growth, relatively resistant to diseases, most commonly available in stores, very nice aroma
  • Midor: needs very wet soil, fast growth, very sensitive to heat, difficult to grow

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