Wasabi is an integral part of Far Eastern cuisine. You can also grow and harvest Japanese horseradish in Germany. Here are our tips.
Wasabi (Eutrema japonicum), like the native horseradish (Armoracia rusticana), belongs to the cruciferous vegetable family. The Japanese particularly appreciate the stem, as it is more aromatic, but also significantly hotter than that of horseradish. Worth knowing: Many gardeners still assume that the rhizome is processed in wasabi. In reality, however, the stem of the plant is used. Depending on the quality of the wasabi paste, leaves and their stems are also processed, which also have a certain sharpness. The wasabi substitute Seiyo Wasabi, which is made from a mixture of horseradish, mustard and chlorophyll, is usually found commercially. Cultivating wasabi in your own garden can not only be worthwhile in terms of taste, but also protect your wallet. A kilo of fresh logs often costs well over €100.
Growing and propagating wasabi in Germany
The wasabi plant also thrives in domestic gardens in our part of the world. In contrast to domestic horseradish, however, wasabi makes slightly higher demands on the soil. This must be moist and not too rich in nutrients. Wasabi doesn't like it too hot in summer, which is why it should be planted in shady to semi-shade. Experienced wasabi lovers grow the plant along streams and rivers. In Japan, too, the highest quality level (referred to as Sawa) is cultivated on mountain streams. If wasabi is regularly grown in fields, this quality level is called oka.
Either grow wasabi from seeds or by dividing existing plants. If you can fall back on the latter, you can enjoy it a year earlier. In Japan, wasabi is propagated almost exclusively by division. During the growth phase, it should only be fertilized extremely rarely (1-2 times a year). Our Plantura organic universal fertilizer is ideal because, as a long-term fertilizer, it supplies its nutrients gently and over a longer period of timeperiod releases. The plant does not tolerate very low temperatures. It is a good idea to protect the plant with brushwood or fleece in winter.
Wasabi Varieties
Although there are a few different varieties in Japan, you can already be lucky if you can buy seeds or plants at all. In the homeland of wasabi, the Daruma and Mazuma varieties are particularly widespread. The Midori variety is more likely to be grown hydroponically, while the Daruma is particularly grown along streams and rivers. Other varieties are: Takai, Medeka and Shimane.
Harvesting and storing wasabi
Here in Germany, wasabi can be harvested after 18 to 24 months at the earliest. If the lying or upright trunk is about a finger thick, it can be harvested. However, only part of the plant should be harvested at a time. The rest can recover and continue to grow. The wasabi plant can then be harvested again the following year. There are no exact figures on the area yield. Researchers assume around 5 to 6 kg/sqm per year in intensive hydroponics. If you want to harvest high-quality trunks, you can count on about 3 kg/sqm every two to three years.
You should only harvest as much as you need directly. The wasabi stems can be wrapped in a damp cloth and stored in the fridge for a few days. Powders, pastes and freshly grated wasabi oxidize quite quickly in air. Especially tubes with wasabi paste should be closed again immediately after opening, freshly grated wasabi should be used immediately.
Ingredients and processing in the kitchen
Wasabi is about 30% water, 25% carbohydrates and about 5% protein. Its calorific value is around 150 to 200 Kcal per 100g. It is rich in minerals such as potassium, iron and magnesium. It also contains vitamins A, C, D and vitamin B12. However, since wasabi is only consumed in extremely small amounts, neither nutrient nor mineral content should have any significant effect.
Only very small amounts of the trunk are required for processing. This is washed thoroughly and then rubbed off. The small and wise flowers that appear between April and May are also edible. Similar to sprouts, they serve as an ideal accompaniment to salads.
Diseases and Pests
So far, the Plantura team has not noticed any diseases on the plants. Merely a meal, presumably by game,may occur in unfenced areas. In the home garden, the plants usually grow without any problems.
If you are a fan of Asian dishes, then in this article you will find out which Asian vegetables we can also grow here.