Wasabi Cultivation
There are two types of wasabi, one grown in fields and the other in water. The latter, known as sawa-wasabi or hon-wasabi, requires very specific water quality and conditions. It grows wild in cold-water streams and can be cultivated only by painstakingly recreating the plant’s ideal conditions: an abundant source of clean water and a relatively constant water temperature. The Azumino wasabi farms were built around springs of pure water from the absorbed snowmelt of the nearby Northern Alps. Shade trees on the banks of the waterways help meet the necessary temperature requirements.
The plant grows steadily with proper care, and despite the drastic changes in seasonal temperatures, can be harvested year-round as long as the water is kept at around 13°C. This is achieved during the hotter months from May to October by hanging porous black cloth over the plants to provide ample shade.
Wasabi Harvesting
At Azumino’s wasabi farms, the plant is grown both from seeds and seedlings, generally taking around 18 months to reach harvestable size. After picking, almost nothing of the plant goes to waste. The stems and roots are chopped up and used in dishes such as wasabi-zuke, a kind of pickle eaten with rice. But it is the rhizome that is the most desirable part of the plant. Grating or chewing it causes a reaction that creates allyl isothiocyanate, the mustard oil that is largely responsible for the spicy jolt to the tongue and nose when wasabi is eaten. Freshness is important, as the peak effects and flavor last for only about 3 to 15 minutes after grating.