Kanuma - Small Grain

Kanuma (Small Grain) – Premium Japanese Bonsai Soil for Acid-Loving Plants

Give your azaleas, camellias, gardenias, and other acid-loving bonsai the soil they were bred for. Kanuma is a soft, highly porous volcanic soil dug from the Kanuma region of Japan, then dried and sifted to size. Its naturally acidic pH and open structure have made it the standard choice for azalea and satsuki bonsai among Japanese growers for generations, whether used on its own or blended into a broader soil mix.

Kanuma is soft enough to break down gradually over a few growing seasons — many growers use that natural breakdown as a built-in signal for when it's time to repot.

Benefits of Kanuma

• Naturally Acidic pH – Ideal for azaleas, camellias, gardenias, and other acid-loving species without added amendments.
• Excellent Water Retention and Drainage – Highly porous particles hold moisture at the roots while preventing soggy, waterlogged soil.
• Visual Watering Indicator – Particles darken when wet and lighten as they dry, making watering easy to monitor.
• Promotes Fine Root Development – Soft particles let roots grow through and around them, building a dense, fibrous root ball.
• 100% Natural and Chemical-Free – Mined and fired only; no fertilizers, pesticides, or synthetic additives.

Ideal Uses

• Azalea and satsuki bonsai
• Camellias, gardenias, and other acid-loving bonsai
• Blended amendment to lower soil pH
• Repotting acid-loving container plants

Particle Size

• Small Grain (1/8" - 1/4")

Available Sizes

• 17 quarts (≈4.2 gallons, 14.35 lb)
• 2 quarts

Why Use Kanuma?

Kanuma has been trusted by Japanese bonsai growers for generations, prized for its balance of moisture retention, drainage, and acidity that few other substrates can match. It remains the go-to choice for azalea specialists and anyone growing acid-loving trees.

Common Application

Use Kanuma alone for azaleas and other acid-loving bonsai, or blend it with akadama and pumice to fine-tune pH and drainage for your climate.