Wasabia japonica. The abundant lore surrounding this Japanese native hints at the inimitable flavor within. Shoguns of the Edo Period, beginning 400 years ago, claimed wasabi as their own and guarded their horticultural knowledge of this finicky and highly valued plant. The geography of the Shizuoka Prefecture, bordered by the Pacific Ocean to the east and Mount Fuji to the north, gives us a clue as to the exacting growing requirements of wasabi. Endemic to banks of fast flowing rivers tumbling down mountains, this favored habitat guides today’s gardener.
Despite such a daunting native environment, we are experiencing a healthy crop in northern California despite our irrigation water and occasional heat. However, 15 minutes in full sun on a July morning wilted all the plants, so full shade is definitely necessary for successful growing. As is constant moisture, high humidity and well-draining soil containing organic material. Occasional pests may nibble on leaves, including cabbage moth and mosquito hawk larvae, snails, slugs and aphids. Fungal disease can attack the rhizomes so watch for any root rot. Temperatures between 40-70 degrees F ideal. Plants go dormant when temperatures are outside this range. Hardy to 28 degrees F.
Given the sensory experience of real wasabi, every requirement is worth the trouble. Even in Berkeley, California, true wasabi is a challenge to find and if you do, expect to pay more than $100/pound. The downside? You'll never be content with the pale green imitation wasabi on offer at sushi restaurants across America. Horseradish, mustard, vinegar and green dye cannot possibly compete with the real thing.
When your plant has several offshoots growing from the main rhizome, you can dig up the entire plant, remove the biggest root and transplant the smaller shoots for your next crop.
Rhizomes are incomparable when freshly dug and grated (find a sharkskin grater if you can). Since the flavor compounds are reactive and volatile, you need to grate right before serving to garner the full wasabi experience. Rhizomes can be stored in the refrigerator for a few weeks before grating.
Leaves taste like firmly textured watercress and are excellent to nibble on, tear into salads, or dip into batter and fry. Don't remove too many because fewer leaves may delay rhizome harvest.
|Wasabi 2 gal|
Wasabia japonica 'Daruma.' This cultivar, 'Daruma', is the most readily available in the U.S. presently because of its relative ease of cultivation. As of November 2017, plants are fuller than photo, with offshoots, but beginning to go dormant. Shipped in 2 gal containers with soil.