We all know wasabi as that green paste served along with our sushi, but surprisingly a lot of what we’ve tried isn’t actually authentic. Did you know you can start growing fresh wasabi indoors or right in your backyard?

Following a step-by-step regime (below) and with the right conditions that wasabi needs to thrive, you'll be able to grow the tastiest “Wasabia Japonica” (Japanese wasabi) around.

So, let’s get on with it.

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How to Grow Wasabi

The wasabi plant requires some mindfulness of specific conditions to flourish. In a nutshell, the humidity index, temperature, and soil conditions all need to be on point.

1. Materials You'll Need

Before you get started planting wasabi, it's essential that you grasp the basics. Here's what you're going to need:

A Greenhouse or Growing Room

This allows sunlight to convert to heat energy that helps wasabi grow properly.

Tarp or Sheet

As greenhouses let sunlight rays through, a tarp is a tent-like shading that will stop direct sunlight on plants.

Sulfur-Rich Fertilizer

Sulfur plays a role in plant metabolism and is necessary as a nutrient for healthy plants.

Distilled Water

Distilled water is free from naturally occurring chemicals in regular tap water. This is to avoid chemical interference with the fertilizer and soil chemistry.

Wasabi Seeds

These are hard to source, but they look like mustard seeds, but obviously green colored.

Roto-Tiller and a Shovel

A machine-powered roto-tiller and manual shovel do the same thing, which is to loosen the soil prior to planting.

2. Preparation: Creating the Right Conditions

Most folks don't want to create a wasabi farm, so in order to create the right growing conditions, you'll need the following:

A humid and Temperate Environment

Only a few places in the world are naturally suitable for growing this picky plant. Wasabi enjoys a wet, warm climate with temperatures between 7°C to 21°C.

Temperature Control Solutions

With a greenhouse, you can trap heat and humidity to control the temperature and adjust settings within the greenhouse to stay between 7°C to 21°C.

During warmer weather, consider using a tarp or shade cloth to the planting beds and, of course, during colder spells, cover them to retain warmth.

An Area With Full Shade

Since these plants grow on the forest floors in their natural habitats, avoid keeping them in direct sunlight. So if you’re planting in a greenhouse, shade them by shaping your tarp/sheet in a hooded structure. If you decide to plant them in a pot, place them out of direct sunlight.

Tending to the Soil

Using a roto-tiller or hand-shovel, fill the soil to about 25cm and fill that up with compost, working it into the soil.

Test the pH of the soil and ensure that it falls roughly between 6 to 7. This ensures your soil isn’t too acidic or alkaline for the conditions the wasabi plant enjoys. Next, work in your sulfur-rich fertilizer to the soil-compost mix and follow the label instructions.

Make Sure the Soil Drains Properly

Though wasabi enjoys moist conditions, it will not do well being waterlogged. To check whether your soil drains well, water the area and if it is absorbed too slowly, then add in some more compost. If the water drains right away, then you’re golden!

Did you know? You’ve probably never eaten genuine wasabi. Most of the stuff at mainstream Japanese Cuisine and Sushi restaurants create a bogus version of wasabi that’s a mix of horseradish, mustard powder, and food coloring, so you’ve got the real deal here!

3. Planting and Caring for your Wasabi

You've got the right growing conditions, now lets look at the growth cycle. how to plant it and care for it.

Buy Seeds in Late Fall/Autumn

Since wasabi seeds aren’t readily available at local greenhouses, order them online around late Autumn, and it can have the winter to get a headstart with good rooting. When they arrive, soak them overnight and plant within 48 hours.

Plant Your Seeds

To plant wasabi, you need to soaking the seeds overnight which will soften their shells, speeding up the germination phase. Sow them about 3-5 cm apart and press gently into the soil. Then, water them liberally once they’re filled in.

Keeping the Soil and Seedlings Moist

To mimic the natural habitat that wasabi blossoms in, spray your wasabi with cool water so that all the plantings are evenly moistened.

If you notice wilting, it suggests they’re drying out, whilst rotting suggests too much water. Thus, you should avoid using a watering can or garden hose, as that could disperse water in higher concentrations.

Look out for any molding or rot. If you spot discoloration and wilting, pull that planting out right away to avoid the spread.

Weed Your Planting Beds

Whilst cultivating wasabi, ensure it has breathing space. Aim to weed out other plants that may be sprouting quickly due to the moist conditions.

Did you know? On an average global scale, restaurants buy wasabi from wasabi farmers at a price of up to $308 per kg. So, once you’re up and running, consider a possible business venture!

4. Harvesting and Using Wasabi

To harvest wasabi you must wait for the right time, otherwise all that time and patience will be for nothing. Here's what you need to do:

Care for Your Plants for Two Years Before Harvest

Like all good things, fresh wasabi also takes time to be at its best. It takes two years to develop its flavorsome taste. After growing about 2 feet tall and wide, it will concentrate naturally on growing a marrow-like rhizome under the soil.

Dig the Mature Rhizomes

The rhizomes or fresh wasabi root is the part of the plant that are grated into wasabi paste. Dig up one wasabi rhizome before proceeding to the others; it should be about 17-20cm long. Be gentle, taking care not to cut into the rhizome - try using a narrow spade.

Leave Some Plants in the Ground to Self-Seed

Leaving a few plantings in the ground will save you the trouble of ordering more seeds. Just remember that once these leftovers begin to sprout, space them about 30cm apart, so they have room to grow.

Using the Wasabi

The leaves and leaf-stalk on the rhizomes can be used for stir-fries and salads, but you can discard them if you wish. After cleaning them, grate off only the amount you think you’ll use. Leave the rest of the rhizome intact to retain the wasabi’s goodness, which would otherwise be lost within a few hours.

Store the Wasabi for Later Use

Keep the wasabi plant stalk in a plastic bag with a damp kitchen towel in the fridge to sustain lasting freshness (up to a month).

Quick Tip! You can always dry them out and grind them down to a wasabi powder. Then mix in a bit of water to form a green paste that’ll pair perfectly with your sushi!

Common Problems When Growing Wasabi

  • Root Rot - Due to the plant’s nature of needing moisture, there is a risk of root rot. The “Planting and Caring for wasabi” section explains what to do if you spot this.
  • Aphids - These pesky so-and-sos are common when growing wasabi, freeloading off the wasabi plants’ stalks and leaves. Simply picking them off or using an organic spray can get rid of this trouble.

Frequently Asked Questions

If you can't find an answer to your question below, get in touch and we'll be happy to help.

What Parts of the United States Can You Grow Wasabi in?

Wasabi can be grown everywhere in the U.S., with just a few things to bear in mind to pave its way for successful blossoming.

Can You Grow Wasabi in Your Backyard?

If you don’t have a greenhouse, you can always grow wasabi in your backyard using leaves as shading.

Can You Grow Wasabi in Pots?

Yes, you can! Be mindful of the temperature, though. If it goes over 26°C or under 5°C, move your plant pots indoors, facing them away from the sunlight. Leaving the pots outdoors for a few days if it’s warmer than 26°C shouldn’t be a problem, but keep an eye out to avoid them losing moisture.

How Long Does It Take to Grow Wasabi?

On average, 15-24 months after planting, you can harvest the rhizome (plant stalk).

Why is Wasabi the Hardest Plant to Grow?

Growing wasabi requires a specific environment to flourish. The humidity, temperature, and soil conditions matter significantly. Additionally, it takes longer for wasabi to grow - about two years. It also requires monitoring as it can be susceptible to rot and disease.

Can you Get Real Wasabi in the U.S.?

True wasabi is hard to find outside of Japan because wasabi seeds are difficult to harvest. You are better off with getting a wasabi plant and growing it yourself. The Wasabi Store is an Oregon Coast wasabi Producer that has got real wasabi Farms!

Can Wasabi Kill You?

No, there are no indications to date that wasabi kills.

Is Wasabi Good for Health?

On average, a serving of wasabi would be about a teaspoon or two, which is too small to have measurable nutrients to impact health significantly. However, authentic wasabi contains more fiber than restaurant-prepared paste, so you’re still better off growing your own!

Is Wasabi Hotter Than Horseradish?

Both have a pungent, tangy, and spicy taste but whilst horseradish tends to have a burning aftertaste, wasabi tends to have a smoother, less harsh, herbal flavor.

Why is Wasabi Eaten with Sushi?

Wasabi contains “allyl isothiocyanate”, a chemical that prevents food poisoning due to its ability to kill harmful bacteria and fungi. Wasabi is usually combined with raw fish, reducing the risk of contracting diseases like listeria.

Conclusion

  • Growing wasabi indoors or outdoors requires certain conditions, making it seem difficult for even those with green fingers. However, it can be done.
  • Creating the right conditions with temperature and soil, followed by a good after-care regime, can give you all you need to become a novice wasabi grower.