Broussonetia kazinoki Seeds | Kozo
LATIN NAME: Broussonetia kazinoki
COMMON NAME: Kozo
Plant Profile
Broussonetia kazinoki, commonly known as Kozo, is a species with a long record in gardens. Pollinating insects take to the flowers at once, adding a little wildlife interest to its garden value. Each of these traits is modest on its own; together they make a garden-worthy plant.
Science & Biotechnology
Seed science, comparative botany and horticultural selection all touch on Broussonetia kazinoki, a representative of the Broussonetia group with clear practical value. This traditional knowledge continues to be actively preserved and studied as part of Japan’s intangible cultural heritage. Centuries of cultivation have left a detailed record of how it grows and behaves.
Uses & Benefits
In the garden, Kozo earns its place in borders, containers and mixed plantings, and it also rewards growers who raise plants for cutting, drying or kitchen use. Kozo bark remains essential raw material for traditional Japanese washi paper, prized for exceptional strength, translucency and longevity in applications ranging from fine art paper to traditional shoji screens and historic document conservation. Growing this species offers a genuine connection to a centuries-old traditional craft still actively practised by washi papermakers today. Once it has its roots down, it more or less looks after itself.
Paper mulberry bark made the world’s first true paper, and in Chinese medicine its red fruits, Chu Shi Zi, are a classical kidney and vision tonic. The leaves serve as forage and the tree is a pioneer of degraded land.
Growing from Seed
Kozo grows readily from seed. Fresh seed germinates most reliably; sow it into a loose, well-drained mix and keep it warm and consistently moist. Bright light suits young shrub well, and it typically establishes readily, in time producing fibrous bark that has made it so significant to traditional Japanese papermaking. Sow on the surface of a gritty, well-drained mix, cover lightly with fine compost, and maintain gentle, even moisture in a sunny position. Pot the young plants on as they grow, harden them off gradually, and plant them into their final positions when sturdy.
Our Take
The traditional uses covered above are what first made this species worth cultivating. Kozo is the kind of plant that rewards a permanent spot. Its wants are few — a sunny spot, soil that drains, and time to settle in.
Related Reading
Gardeners who grow Kozo often pair it with these related subjects: