Japanese paper mulberry

Family

Moraceae

Habit

Shrub

Height

4.5 m

Spread

4 m

Growth

medium

Lifespan

50 years

First yield

after 4 years

Hardiness

zone 6–9

Shade tolerance

full sun

Soil

Sand, Silt, Loam

Soil moisture

semi-dry – very moist

pH

5.5 – 7.5

Synonyms

Broussonetia kazinoki Siebold

Edible: The red, rounded fruits turn sticky and very sweet at full ripeness; their aroma is described as a mixture of white mulberry with a faint fig note. Unlike the closely related paper mulberry, the fruit is edible in its entirety and not confined to the fleshy outgrowths. Ripeness is decisive: fruit that is not quite ripe tastes grassy and none too pleasant. The individual fruits stay small at about a centimetre and yield little flesh, but the aroma is regarded as exceptionally fine. Young leaves are cooked and used as a vegetable, and the flowers are considered edible as well.

Other uses: For over a thousand years the bast has supplied the fibre for high-grade East Asian handmade papers and is regarded there as the preferred source for that purpose. Cloth and rope are made from the fibres as well. Accounts differ as to fibre quality compared with the paper mulberry; for fine papers, however, this species is preferred in its regions of origin.

It calls for a sunny, warm position on free-draining soil of medium quality; air pollution is well tolerated. Growth stays shrubby and open, reaching two to four and a half metres in cultivation. The young growth in spring is frost-sensitive — a position without early morning sun reduces damage after night frosts. Winter hardiness is reported inconsistently: usual ratings go to about minus fifteen degrees, while one practical account from a garden with several years of experience gives minus twenty-five degrees without damage from late frost or other weather extremes. The attempt is therefore worthwhile in harsher positions, without being something to rely on. Plants are monoecious or dioecious; fruit set generally requires both sexes.

Semi-ripe cuttings in July and August root reliably and are the easiest route. Cuttings of ripened wood are taken in November; root cuttings and layering shoots in spring are equally possible. In the regions growing it for papermaking, propagation is traditionally almost entirely vegetative, because the shoots are harvested before flowering. Sowing is possible: sow in autumn or spring under glass, with germination at about fifteen degrees within one to three months. Since this is a hybrid, seedlings come out variable — anyone wanting to preserve a particular form depends on vegetative propagation.

A hybrid of hime-kozo and the paper mulberry that was long held to be a species in its own right; molecular studies have only recently confirmed its hybrid origin. Both parent species carry the same German common name, which explains the persistent confusion. It differs from the large-growing paper mulberry in its consistently shrubby habit, shorter leaf stalks, shorter male inflorescences and markedly less hairy young shoots. The practical difference lies in the fruit: here it is edible in full, whereas in the paper mulberry only the fleshy fruit filaments offer anything.

East Asia: the hybrid occurs within the natural range of both parent species and has been cultivated in Japan and Korea for centuries. It probably reached Europe in the nineteenth century but has always stood in the shadow of the larger paper mulberry here and is rare in the trade.

Grows in warm, favoured positions along woodland edges, in open woodland and on waste ground, mostly on free-draining, moderately fertile soils. As a crop plant it stands predominantly in tended plantations where the shoots are harvested annually, and in gardens. Urban climate and polluted air are well tolerated.