Grow Wasabi

Wasabi (Japanese horseradish) [Wasabia japonica ] is grown by two methods: field flooded or in soil. Most likely in your own garden it will be easiest growing it in soil, but if you are able to grow hydroponically, your choices are broadened. This article focuses on the soil method; the hydroponic method is trickier and requires specialist knowledge (but feel free to add this to the article if you have the expertise!).

Steps

 * 1)    Ensure that you have an area of soil that is well drained and drains easily. Soil-grown wasabi doesn't tolerate having wet feet. Wasabi prefers shaded areas.
 * 2)  Add a lot of compost to the soil and work it through.
 * 3)  Obtain seeds. Keep moist and plant within 48 hours of receipt. Soak seeds overnight prior to planting.
 * 4)  Plant wasabi seeds (or seedlings if you started indoors) into the soil. Plant 2.5 m – 5 m / 1" - 2" apart. If you are planting seedlings, water the roots prior to planting. Water well and keep misted daily. Winter is the best growing season for wasabi, so autumn (fall) is the ideal time to plant.
 * 5)  Keep well irrigated during the hot months. Ensure that the soil is draining well. Don't let the roots dry out or they will taste bitter.
 * 6)  Keep well weeded. There should be no need to spray unless you have aphids–use a natural aphid spray if needed.
 * 7)  Be patient. Wasabi takes around 18 months to two years to reach maturity.
 * 8) Harvest. Wasabi should be removed by digging up with a pitchfork. Be sure to get the rhizomes which contain the greatest concentration of flavor.
 * 9)  Leave some plants in the soil to self seed. If the conditions are right (not too hot, dry, etc.), once wasabi is established in your garden, it should continue to grow well and self-seed continuously.

Tips

 * If you have heavy soil, add some lime as well as the compost.
 * Wasabi seeds must be stored moist (keep in fridge). Once dry, they tend to not grow.
 * Locating seeds can be difficult; find a farmer growing wasabi and kindly ask for some seeds. Alternately, visit a Chinese or Japanese grocery store and ask them if they can provide you with the seeds or seedlings.
 * Wasabi prefers high humidity and does not grow well in dry, very hot weather. You might need to provide misters if you have very hot weather.
 * Store the harvested roots in plastic bags in the fridge for up to two months post-harvest.

Warnings

 * Wasabi is prone to slugs, especially in the early growing stages. Deter and remove them.
 * Aphids like wasabi. Treat with an aphid spray.
 * Black rot can threaten wasabi plants; take care not to leave the plants sitting in waterlogged soil.
 * Wasabi leaves and leaf stems (petioles) are brittle. Any breaks or disturbances can slow and stop growth.
 * Cats can be attracted to wasabi leaves.

Sources and Citations

 * Wikipedia on Wasabi.