Growing Wasabi in Polytunnels at Wasabi Crop

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Wasabi Crop has embarked on an ambitious journey to cultivate authentic wasabi in the heart of Northern Ireland, a feat many might have thought improbable given the plant’s notorious difficulty growing outside its native Japan. However, through innovative agricultural practices and the utilisation of polytunnels, Wasabi Crop has succeeded in this endeavour and set a new standard for local wasabi production. This essay delves into the methods and techniques employed in growing two varieties of wasabi, Mazuma and Midori, within the confines of six polytunnels, showcasing the blend of tradition and innovation that characterises our approach.

The Challenge of Wasabi Cultivation

Wasabi (Wasabia japonica), often referred to as Japanese horseradish, thrives in specific conditions that are hard to replicate. Traditionally, it is grown in the mountainous river valleys of Japan, where the water is pure, and the environment provides the perfect balance of shade, humidity, and temperature. Outside of these regions, the challenge is to mimic these conditions as closely as possible to encourage the wasabi to grow as it would in its natural habitat.

Polytunnels: A Controlled Environment

At Wasabi Crop, we have turned to polytunnels as a solution to this challenge. Polytunnels essentially elongated polyethene-covered tunnels, offer a controllable growing environment that can be adjusted to meet the specific needs of the wasabi plant. Within these structures, temperature, humidity, and light levels can be manipulated to create an optimal growing environment, mitigating the often unpredictable Northern Irish weather.

Our Varieties: Mazuma and Midori Wasabi

We focus on two varieties of wasabi: Mazuma and Midori. Mazuma wasabi is prized for its robust flavour and vibrant green colour, making it a favourite among chefs and food enthusiasts. Conversely, Midori is known for its milder taste and is often used in traditional Japanese dishes that require a subtler wasabi presence. Both varieties demand meticulous care and attention to detail, traits that our team at Wasabi Crop possesses in abundance.

Cultivation Techniques

Growing wasabi in polytunnels begins with the careful preparation of the soil to ensure it is free from contaminants and rich in the nutrients wasabi plants crave. We employ a hydroponic system that allows us to control the amount of water and nutrients the plants receive, mimicking the flowing water of their natural habitat.

Light is another critical factor in the growth of wasabi. In their natural environment, wasabi plants are shaded by the forest canopy. We replicate this condition using shade cloths, ensuring our wasabi receives the right amount of light without being exposed to the harsh direct sunlight that can scorch the leaves and stunt growth.

Temperature and humidity are closely monitored and adjusted as needed. Wasabi prefers a cool climate with temperatures ideally between 8°C and 20°C. Our polytunnels are equipped with ventilation systems that can introduce cooler air from outside or recirculate the air within to maintain these temperatures. Humidity levels are kept high to replicate the moist conditions of a river valley.

Harvesting and Quality Control

The journey from planting to harvest is slow, with wasabi plants typically taking between 18 months and two years to mature. This patience is rewarded with a product of exceptional quality and flavour. Harvesting is done by hand to ensure that the plants are not damaged, and each root is inspected for quality before it reaches the consumer.

Quality control is paramount, as Wasabi Crop’s reputation rests on the excellence of our product. Each stage of the growing process is carefully documented and reviewed to ensure that any issues can be quickly identified and addressed.

Sustainability and Innovation

Sustainability is at the core of our operations. The controlled environment of the polytunnels allows us to minimise the use of water and nutrients, reducing our environmental footprint. We are constantly seeking ways to improve our processes, experimenting with new techniques and technologies to enhance the quality of our wasabi and the efficiency of our production.


The cultivation of Mazuma and Midori wasabi in the polytunnels of Wasabi Crop represents a remarkable fusion of traditional agricultural practices and modern technology. By carefully controlling every aspect of the environment, from the soil to the air, we have created a small slice of Japan in Northern Ireland, allowing us to produce wasabi that rivals that grown in its native habitat. This endeavour showcases the potential for diverse agricultural practices in the region and brings a unique and sought-after product to the global market. As we continue to refine our techniques and expand our knowledge, the future of wasabi cultivation at Wasabi Crop looks as bright and green as the wasabi itself.

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