growing conditions that restrict its wide cultivation - among other things, it is quite intolerant of direct sunlight, requires an air temperature between 8 and 20 C, and prefers high humidity in summer. This makes fully satisfying commercial demand impossible for growers, which makes wasabi quite expensive. Therefore, outside Japan, finding real wasabi plants is rare.

A common substitute is a mixture of horseradish, mustard, starch, and green food colouring or spinach powder. Often packages are labelled