What is Igusa (Rush Grass)? Understanding its Uses and Benefits

What is Igusa (Rush Grass)?

Igusa, known in English as rush grass, is a monocotyledonous plant that grows in wetlands and shallow water. It has been naturally present around the world for centuries, with nearly 300 known species. In Japan, the plant's long stems, which can grow up to 150 cm (about 5 feet) , are harvested and used primarily for making tatami mats and woven straw mats known as “goza.”

The History of Igusa in Japanese Culture

The exact time when humans first started using igusa in their daily lives remains unclear. However, it is believed that the Japanese have been utilizing igusa since the Jomon period, using it similarly to how we use textiles today. In modern times, igusa is mostly cultivated in Japan’s Kumamoto Prefecture, which produces over 90% of domestically grown igusa. Unlike crops grown from seeds, igusa is cultivated through a unique process involving plant division, and only those grown in the main fields are used for products.

Why Is Japanese Igusa Special?

While imported igusa has become more common in recent years, Japanese-grown igusa is renowned for its superior durability, elasticity, and soft texture. In 2016, igusa used in tatami mats produced in Kumamoto was registered under the Geographical Indication (GI) Protection System by the Ministry of Agriculture, Forestry, and Fisheries of Japan. This GI system ensures that agricultural products and foods associated with a specific region are protected as regional brands, similar to Champagne or Parmigiano Reggiano.

The Significance of GI Registration

For those unfamiliar, the Geographical Indication (GI) Protection System is a framework that registers region-specific agricultural products and foods. By giving these products a special status, it protects regional brands and promotes the unique qualities associated with their place of origin. For Kumamoto-grown igusa, GI registration highlights its cultural significance, high quality, and the dedication of local farmers to preserving this traditional craft.

The Growing and Harvesting Process

Igusa is planted between late November and late December. Once the stems have sufficiently grown, the harvest season begins, usually from late June to mid-July. The harvesting process is meticulous:

1. Timing: To prevent quality deterioration, igusa is harvested early in the morning or during the evening.
2. Dyeing and Storage: Post-harvest, igusa is dyed with a special mud dye and then dried before being stored in preservation bags.
3. Aging: Freshly harvested igusa is firm and difficult to dye or weave. However, after being stored for a year, the fibers become more flexible and are less prone to discoloration, making them ideal for creating high-quality mats.

Photo of mud-dyed Igusa (rush grass)

The Functional Benefits of Igusa

Igusa offers several unique benefits, which are why it has remained a part of Japanese culture for centuries:

1. Humidity Regulation: Igusa can absorb and release moisture, helping to maintain an optimal humidity level indoors.
2. Air Purification: It absorbs harmful substances in the air and acts as a natural deodorizer.
3. Relaxation Effects: Igusa releases a scent similar to a forest bath, offering relaxation and stress relief.
4. Shock Absorption: Its natural elasticity provides cushioning, which helps absorb impacts.
5. Antibacterial Properties: Igusa’s natural antibacterial properties help prevent odors and foot fungi.

Kohaku’s Commitment to Igusa

At Kohaku, we use 100% domestically grown igusa from Kumamoto Prefecture. By modernizing tatami products, such as our tatami yoga mats, we aim to create new demand and contribute to the local industry by purchasing igusa from Kumamoto farmers. Incorporating igusa into your life not only supports Japanese agriculture but also brings a touch of nature and serenity into your daily routine.

For more insights on the benefits of tatami and how it can enhance your well-being, check out our related articles. Let's enrich your lifestyle with the timeless beauty and functionality of igusa.

Sources: Various studies on the benefits of igusa, Kumamoto Prefecture agricultural records, and the Ministry of Agriculture, Forestry, and Fisheries of Japan.