This hardy, slow growing herbaceous perennial takes 18-24 months for the rhizomes to reach a usable size. The plants will grow to a height of 30-60cm (12-24″) with a spread of approximately 30cm (12″).
Wasabi plants dislikes sun and should be grown in a humid, shady position where the soil is boggy and rich in organic matter. The soil must never dry out as the plants will quickly suffer. Space the plants about 30cm (12″) apart and apply a thick mulch of organic matter. Slugs and snails can be a problem and steps should be taken to avoid attacks.
Wasabi grows most rapidly at temperatures between 7-8°C (45-64°F) in spring and autumn. To extend the growing period cover the plants in winter with fleece. The plants will produce offshoots which can be grown on for future crops.
The rhizomes are harvested when they are about 10-15cm (4-6″) in length and 1-2cm (½-¾″) in diameter. The intact roots will keep in the refrigerator for up to 30 days and dried roots for several months. Wasabi is best grated fresh at the table as it quickly loses its flavour within a few hours. It is often used in soups and marinades.
It is possible to grow the plants in large pots of aquatic soil stood in a large tray of water which is regularly topped up.