The best way to develop wasabi: advanced however rewarding

For sashimi or sushi, wasabi is king – and yet very little of what people in the United States buy as "wasabi" is real wasabi, as real wasabi is known to be a very tricky plant. Usually, the light colored wasabi paste in these tubes is actually European horseradish with food coloring! But for lovers of Japanese food, it is worth growing real food. Freshly grated and full of nutrients, it's difficult but doable once you know how to grow wasabi.

As a member of the Brassica family, this Wasabia japonica is a cool weather loving grower. It is native to areas adjacent to streams in mountainous Japan. You need to simulate the rocky, moist, and well-drained environment in which this plant first evolved. Shade is absolutely necessary, as is slightly sulphurous soil and very consistent watering and weeding. Wasabi is grown from rhizomes and can take a few years to grow. While it's difficult to sow yourself, most people end up finding little plants to get their harvest going.

Many areas of the Pacific Northwest and British Columbia successfully farm this plant, where islands of leaves and roots live in heaped gravel beds as the water flows steadily by. There are actually 18 varieties of wasabi, although you will most likely only find Mazuma or Daruma varieties in the US.

People successfully grow wasabi year after year, either in greenhouses or in very shady areas of their garden. While it takes roughly two years for your plants to produce fruit, growing this green-tinged rhizome at home is perfectly feasible, and in the meantime, you can harvest some delicious foliage too!

Good products on Amazon for growing wasabi:

Brief instructions for care

The process of how to grow wasabi is a bit complex. Source: Andrew McLucas

Common name (s) Wasabi, yama, ooi, Japanese horseradish
Scientific name Eutrema japonicum, syn. Wasabia japonica
Days to harvest 12-48 months
Bright No direct sunlight, just filtered light
water 3-4 ”per week
floor Well-drained soil rich in humus or gravel with a soil pH of 6.0-7.0
fertilizer Well balanced 12-12-12
Pests Aphids
Diseases Leaf spot, root rot, rhizome rot & leaf stem rot

Everything about wasabi

Wasabi seedlingA young wasabi seedling. Source: Unconventional Emma

Wasabi originally comes from Japan and is now known worldwide for its sushi popping qualities. This root is ground into a paste and served with a wide variety of fish or vegetarian sushi. While this root was originally used for consumption with fish for its antibacterial properties, it is now used as a spice rather than a food-safe disinfectant.

The wasabi plant or Eutrema japonicum grows from an underground rhizome along stream beds in shady areas and in cool temperatures in mountainous Japan. Since this is a slow growing plant, it can take several years for the entire plant to reach maturity. The wasabi roots are the coveted part of the plant, although the whole plant is consumed.

The health benefits of the actual plant, when grown at home from seeds or rhizomes, are undeniable. Originally only eaten with raw fish, this plant is also eaten for its leaves, which can be added to a dish called azuke with sugar and salt. Alternatively, the leaves can be boiled or eaten in salads.

Slightly strange looking plants, fresh wasabi is grown in aquaponics, a soil that does not hold back water or even gravel. The wasabi rhizome grows underground and can resemble a swollen taproot that protrudes from the ground when fully formed and ready to harvest. Rhizomes are 1-2 inches wide and up to 18 inches deep. They sprout several long petioles that can grow up to 24 inches tall. Large, heart-shaped, light green leaves rest boldly on their stems and soak up the little light this plant needs. Although it doesn't always bloom, the plants can bloom in early spring and produce more seeds that can then be used for propagation. While it takes up to 60 days for the seed pods to ripen, they form along long, thin stems and can look like tiny pea pods. There are roughly 2-6 seeds per pod.

Because of the part of this world these plants evolved in, when growing wasabi from seeds, you need to layer the seed. Make a bogus winter by putting it in the refrigerator for up to two months. This process helps the seed know when it is time to go out of dormancy and sprout.

Wasabi. plant

If you grow wasabi from plants, i. H. Smaller outgrowths on a rhizome of a larger wasabi plant are best started in autumn. Wasabi grows most in the cool season, namely between autumn and spring, when temperatures are cool and plants are most likely to receive steady water (either rainwater or distilled water).

In late autumn, place your plants in well-drained soil, gravel or a vermiculite-like root medium. The wasabi root is generally considered very difficult to cultivate and is more commonly propagated through vegetative propagation – the plucking of smaller plants from the crown of the mother plant and placed in ideal, moist and shady conditions to create a whole new range of wasabi. to create plants. This is believed to be the fastest way to grow large quantities.

While this semi-aquatic plant is widely grown in the United States in the Pacific Northwest along the Oregon coast, it can be grown both in aquaculture and in an elevated planting bed with organic soil and a very well drained planting medium. Wasabi need an environment that somewhat mimics the growth medium in which they evolved along river beds. So running water is ideal, hence the popularity of aquaponics. If these conditions are denied, wasabi will primarily fall victim to fungal diseases as the wet soil breeds a wide variety of diseases.

To plant, try the tatamishi system, a Japanese rock mat system that provides running cool water where the earth drains quickly. The beds can vary in width and length, but are made up of a layer of 2 "of sand, over 3" of gravel, with 16-40 "of small rocks as the bottom layer. Inside the bed there is a gradient of 1-4 percent that encourages a constantly flowing jet of water. It is best to transplant small plants when they are about 1.5 inches tall and have 4-5 true leaves germinated.

Many growers also plant wasabi in containers. Wasabi growing can be more easily controlled in this type of environment as less gravel, sand, or drainage medium is needed to control the growing environment. Growers will also use shade cloths to protect their new plants from direct sunlight, or place them in full shade in a greenhouse.

If growing in the ground, transplant plants that are at least 2 inches deep for their long roots into containers that are deeper than usual. The root needs more space than most to grow.


Wasabi fieldA wasabi field. Source: electricnude

Growing wasabi can be quite tricky as it is known to be one of the most difficult plants to grow. However, given sufficient time and careful cultivation, a rhizome can produce a much larger harvest. This edible rhizome is very easy to care for and needs a gardener who tries to best reproduce these conditions.

Sun and temperature

Wasabi thrives in mild temperatures. Wasabi leaves need a shady location out of direct sunlight and a temperature range between 46-70 degrees Fahrenheit. Wasabi plants can die above 80 degrees, while wasabi plants can freeze below 27 degrees.

Try to recreate these conditions by providing shade in the form of a shade cloth or a large tree shade. Add compost to your growing medium to a depth of 10 inches to both provide nutrients and isolate the roots from extreme temperature changes.

Water and moisture

Wasabia japonica continuously needs water to be delivered to its root zone. It is the ideal plant for growing in a water garden or in containers where the soil can be kept moist at all times – more moist than many other plants can handle. Many growers outside of the Pacific Northwest containerize these for precisely this reason, as their temperamental nature requires special attention for the duration of their lives.

Wasabi is not drought tolerant at all. You need to provide a continuous source of moisture if you want to harvest wasabi. Given the growing conditions in which it evolved, it is best to mimic a humidity level between 90-95%.


Wasabi is not grown in traditional potting soil. For this growing endeavor, you'll need to find a very well-drained growing medium like vermiculite, sand, and gravel, or even try the aquaponics route.

You can try growing in the tatamishi system described above, or directly in gravel along a stream, or in a 50/50 mix of sand and gravel in growth containers. Given the difficulty of growing this particular plant, it may be best to try a few growing methods at the same time and see which is best for your growing environment.


Wasabi doesn't need a lot of fertilizer. They grow slowly and therefore cannot absorb too much fertilizer. However, it is best to give them a balanced fertilizer (that is, the NPK numbers are all the same) like 12-12-12 at the time of transplanting. In addition, many farmers apply a foliar spray to the leaves about 1-3 months before harvest to improve the taste.


Although it is difficult to grow from seeds, it is possible. Known for their low germination rates, if you get some of the seeds or seed coats try overplanting and expect to undergrowth. Additionally, if they haven't been layered, you will need to put the wasabi seeds in the refrigerator for 2 months to simulate a cold spell when the wasabi seeds are dormant. You can expect a germination time of 3-4 weeks.

It is more likely that you will find or be able to find puppies, little plants, or starts (all the same). These are the baby plants that grow along the stem or crown of a more mature wasabi plant. With these starts, you can place them right in your growing medium to ensure that the root has enough room to grow down. This is best done in the fall, with several months of ideal growing conditions on the horizon.

This option, also grown by tissue culture, is open to many large scale farmers who want to grow sterilized produce faster without spreading some of the many diseases that are common in the culture. This is a relatively new way of propagating plants, and not something that can be reproduced outside of a laboratory. In your wasabi search, try looking for wasabi tissue culture plants if you can't find the more traditional starts.

Harvest and storage

Wasabi rootsWasabi roots are the price that everyone strives for. Source: tonnoro

The easiest part of growing is enjoying the fruits of your labor!

Harvest & storage

Wasabi is actually edible in almost every phase of life. However, it is usually harvested when the stems are about 4-5 inches above the ground and about 1 1/2 inches thick. Just gently pull the stem out of the ground trying not to break it in two. Remove the leaves and any rot at the roots.

It is best used fresh and eaten raw after it has been grated. It usually only keeps fresh in the refrigerator for around two months. Alternatively, it can be dried and pulverized, but doing so will cause the plant to lose some of its valuable nutrients. There are no idle servings of wasabi as the entire plant is edible. Try adding its leaves and stems to a salad or pickling them to make azuke.


Close up of wasabi leavesA close-up picture of wasabi leaves. Source: mannewaar

Since this is a difficult plant to grow, you may encounter some problems in the 2+ years that you have grown wasabi.

Growing problems

One of the most common problems with growing wasabi is finding root rot. To combat this problem, look for rot-resistant starters. There are several varieties that have been bred to be resistant to rot. Improve drainage in your growing area and remove dead leaves that can harbor disease once they are dead and decay.


Wasabi doesn't suffer from too many pest problems. You are much more prone to fungal problems. However, Aphids are big fans of the wasabi leaf. Neem oil or insecticidal soap will handle the aphids easily.


Wasabi suffers from a variety of fungal diseases including Leaf spot, Root rot, Rhizome rot & Leaf stem rot. It can be difficult to distinguish between the diseases as many of them manifest with the same symptoms of withered leaves, browning and blackening of the stems and roots, and a greyish tinge to the leaves. Prevention is the best way to go as few plants survive the disease, especially considering how long it takes to harvest. Use a copper spray as a prevention against leaf spots.

frequently asked Questions

Wasabi in flowerWasabi flowers are relatively inconspicuous. Source: no

Q: How long does it take to grow wasabi?

A: 1-3 years on average.

Q: Is it hard to grow wasabi?

Answer: yes. But it's worth it when you get a harvest!

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