Try Growing Your Own Wasabi Indoors
As you can see from the photo above growing wasabi indoors can be done without a lot of expensive equipment. The above system is OK for a couple of plants, but for commercial operations it is not really feasible or economic to use such a system.
Also with the above setup the window should be facing North (in the Northern Hemisphere) and to the South (in the Southern Hemisphere). It should not receive any direct sun and may need a sunscreen to keep the sun off the plants during the summer periods.
The information below can be applied to the system above as well as to small commercial systems (up to 10,000 plants).
Growing Wasabi Outdoors
Most of the worlds Wasabi (Wasabia japonica) is grown outside in the ground with minimal protection from the weather.
This ground grown Wasabi produces a low quality product with variable growth rates, coupled with a tendency to become disease ridden which can completely destroy the whole crop.
Growing Wasabi Indoors
There are some growers (most notably World Wasabi Inc.) that has been growing Wasabi indoors using hydroponics since they started up in 1990. There are now a few more who have also implemented these growing systems to produce Wasabi for the discerning Connoisseur.
As Wasabi is a semi-aquatic plant, it is well suited for hydroponic production in a scalable manner. Quality, yield and growth rates can be improved by the use of indoor hydroponics if the right growing conditions are provided. At the moment young Wasabi plants are available from a number of places, such as the Internet and some commercial wasabi growers.
What growing conditions are needed to grow Indoor Wasabi?
Wasabia japonica has a reputation as being the most difficult plant or herb to grow to a usable product. Much of this reputation arises from the fact that Wasabi requires cool growing conditions and has almost zero heat tolerance. This environment is almost the opposite of most plants that hydroponic growers are used to supplying their crops.
These specific requirements now needs the prospective indoor grower to look at supplying a highly controlled environment to give optimal results.
In its native environment in the Japanese mountain streams, the Wasabi plants are commonly grown under shade trees with its roots partly immersed in the streams flowing waters. A number of commercial wasabi growers around the world have tried to copy these conditions with varying degrees of success.
When attempting to grow Wasabi indoors, the plant not only needs a cool environment but also a significant air flow over and through the plants.
Another thing that needs to be thought about is the fact that Wasabi grows in the shade. Therefore care needs to be taken to select the correct lighting to use (if necessary). Hot, direct HID lighting may burn Wasabi foliage and cause too much heat damage on the plants. LEDs similar in intensity to those used for micro greens and lettuce should be looked at as a suitable replacement.
Wasabi requires similar temperature growing conditions to other cool season crops such as lettuce and other salad greens (50 to 72°F, 10 to 22°C). Growing Wasabi in such an environment with a better control of the maximum temperatures reached within an existing growing facility for these type of crops is possible.
Warmer growing conditions with result in leaf wilting, reduced growth rates and eventually death of the Wasabi plant. Reducing the air temperature using fog or misting systems have been shown to be useful in reducing these air temperatures.
Hydroponic Systems for Small Scale Wasabi Production
By small scale Wasabi production we are talking about less than 10,000 plants in total. For larger number of plants then a more detailed growing operation will need to be designed to suit the specific environment. Contact Michel Van Mellaerts (The Wasabi Maestro) at michel-at-wasabi.co.nz for assistance.
The Wasabi plant can get quite large when it is reached maturity and is ready to harvest. From the point where you plant the Wasabi seedling it is not unusual for the leaves to cover and area of at least 2 – 3 feet (600 to 900 mm) and be 2 feet (600mm) high. You have to space your small plants properly to take the spreading nature of the plant into account.
When a growing bed is ready for harvest the surface will be totally obscured with a dense canopy, and will make moving around on the growing bed difficult without damaging the Wasabi plant. The Wasabi leaves can grow to the size of dinner plates and are supported by thin, very brittle stems which are easy to break.
Too much damage to the petioles (leaf stems) can kill the Wasabi plant so care must be taken in handling and harvesting the crop.
Some species of Wasabi have a single rhizome where others can have a main rhizome with a number of offshoots. The small offsets or shoots can be replanted to grow into a mature plant. However there are only a finite number of times this can be done before the resulting plant is not able to be sold.
Other species have a single rhizome and these are commonly grown for the restaurant table market.
The Wasabi root system also become large, dense and heavy. It is likely to block the channels of a nutrient film system.
The Wasabi plant does not do very well in a growing system where the roots are continually submerged and/or the liquid is allowed to stagnate.
The growing media used in these systems can consist of any sterilised coarse substrate that provides free drainage and remains highly aerated.
Wasabi is prone to fungal disease and stem rots if the growing conditions become too wet due to excessive irrigation. The most common problem is a disease called “Blackheart” which turns the inside of the rhizome black and unusable. This is not always evident until the rhizome is cut or grated.
Nutrient Requirements for Wasabi
Regular changes of the nutrient solution for Wasabi is advised to maintaining the growth rate. If you notice that the EC levels in the solution has stopped dropping, then that is the time to change the nutrient solution. This is likely to cause a growth spurt and an increase of the nutrient uptake.
As a member of the crucifer family, Wasabi has similar nutrient requirements with the addition of a sulphur spray occasionally through the growing season and in the three months prior to harvest. This helps to develop the compounds that give Wasabi its distinctive taste and flavour.
Wasabi has similar nutrient requirements to other members of the crucifer family and the addition of extra sulfur during the stem development and elongation phase may assist the development of volatile compounds within the plant tissue.
Wasabi Planting and Propagation
Wasabi seeds are available, but due to the difficulty in actually germinating them it is recommended that offsets from the previous crop or rooted shoots or cloned plants are used. Most Wasabi seeds currently advertised for sale on the Internet are actually Mustard or weed seeds.
Japan apparently will sell Wasabi seeds but applications needs to be made to the Trade Office of the Japanese Embassy. Even so, they will likely not make any available.
Offsets should only be used for a maximum of three crops before new plants are used.
These new plants should be cloned plants or other virus free plants from a reputable supplier.
There are 17 few different wasabi cultivars, but only two cultivars are commonly grown commercially. These are Daruma which produces single rhizome, and Midori which produces multiple offsets but doesn't look as pretty.
Harvesting and Preparation of Homegrown Wasabi
The whole of the Wasabi plant can be used, but the rhizome (Swollen stem) of the part is the part most commonly recognised as Wasabi. The stem grows on the surface of the growing media over a 12 to 18 month period. It creeps along putting down hair roots while the growing tip and the source of the leaves moves with it.
The older leaves fall off as it grows leaving leaf scars behind. The longer it is left to grow the larger the rhizome becomes, but the chance of it contracting a disease and dying also increases. We have grown a Wasabi stem to over 2 feet (600mm) long with a diameter of 1.5 inches (75mm) weighing 1.25 Kilo (~3 lbs).
The whole Wasabi plant must be carefully removed from the growing media and then the dense hair roots removed with a sharp knife. The petioles (leaf stem) removed and the leaves separated, before the rhizome is scrubbed to remove the discolouration covering the surface of the rhizome.
The above rhizome still needs to be further trimmed, top and bottom before being scrubbed to remove the patina and dark colouring between the leaf scars. It is then ready for sale.
Fresh Wasabi rhizomes have a limited shelf life and once cut from the plant should be refrigerated and kept in a damp atmosphere. In a refrigerator they will keep up to 10 days, and freezing them destroys the cell structure and they lose their flavour.
Traditionally, the Wasabi rhizome is grated just before being consumed as the flavour disappears after about 15 minutes after being grated. The finer the grater the more intense the Wasabi flavour and the nose rush. The grated paste should be left for approximately 5 minutes for the chemical reaction to take place that produces the Wasabi kick.
After all the hard work about growing and looking after the plant, this is what the final result looks like.
The finer the grater the more pungent the famous Wasabi flavour is. Traditionally Sharkskin is used, but with the overfishing of sharks it is better to use a fine metal nutmeg grater instead.
All parts of the Wasabi plant be used. The Wasabi leaves are a great favourite with Restaurants and the petioles, small offsets and roots can be used in processing to make Wasabi sauces, pastes and other items that require a Wasabi flavour or extract.
Most of the so called “Wasabi” pastes, powders and flavours are not derived from Wasabia japonica but from Horseradish, Mustard and colouring. There is no comparison in the taste between the True Wasabi and the Fake wasabi. Get The Wasabi List below for more information.
Growing Wasabi for your own use can be enjoyable and rewarding, while growing it commercially can be profitable as well.
Being careful and attentive to maintain the environmental controls, and a great deal of attention to the health of the Wasabi, it will grow well in a hydroponic system.
Get a free copy of The Wasabi List which contains a list of over 80 "Wasabi" products that do not contain any Wasabia japonica at all, except for in the name of the product.
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