Common Name: Walnut

General Information

Juglans sigillata is a deciduous tree that can grow up to 25 metres tall.
The plant is closely related to the common walnut and, like that species, is cultivated as a commercial seed crop, especially in China. The plant also produces a valuable timber.

Known Hazards

None known

Botanical References

Range

E. Asia - northern India, Bhutan, China (Guizhou, Sichuan, Yunnan, southeast Xizang)

Habitat

Forests in valleys and on mountain slopes; at elevations from 1,300 - 3,300 metres[, ].

Properties

Edibility Rating
Other Uses Rating
Habit	Deciduous Tree
Height	30.00 m
Pollinators	Wind
Self-fertile	Yes
Cultivation Status	Wild

Cultivation Details

The dormant plant is very cold-tolerant, but the young growth in spring, however, can be damaged by late frosts.
Requires a deep well-drained loam and a sunny position sheltered from strong winds[, ]. Prefers a slightly alkaline soil[].
Plants produce a deep taproot and they are intolerant of root disturbance[, ]. Seedlings should be planted out into their permanent positions as soon as possible and given some protection for their first winter or two since they are somewhat tender when young[, ].
Flower initiation depends upon suitable conditions in the previous summer[]. The flowers and young growths can be destroyed by even short periods down to -2°c, but fortunately plants are usually late coming into leaf[].
Any pruning should only be carried out in late summer to early autumn or when the plant is fully dormant otherwise wounds will bleed profusely and this will severely weaken the tree[].
Trees have a dense canopy which tends to reduce plant growth below them. We have no specific information for this species, but the roots of several members of this genus produce substances that are toxic to many plant species, especially apples (Malus species), members of the Ericaceae, Potentilla spp and the white pines (certain Pinus spp.)[]. The leaves of many species also secrete substances that have an inhibitory affect on plants growing underneath them. All in all this is not a very good companion plant[].
This plant is cultivated for its edible seed in China[, ].
This species is notably susceptible to honey fungus[].

Edible Uses

Seed - raw or cooked[]. The thick and hard-shelled, subglobose nuts are around 34 - 60mm x 30 - 50mm, produced in clusters of 1 - 3[].

An edible oil is obtained from the seed, it tends to go rancid quickly.

Medicinal

None known

Agroforestry Uses:

Plants produce chemicals which can inhibit the growth of other plants. These chemicals are dissolved out of the leaves when it rains and are washed down to the ground below, reducing the growth of plants under the tree[, , ]. The roots also produce substances that are toxic to many plant species, especially apples (Malus species), members of the Ericaceae, Potentilla spp and the white pines (certain Pinus spp.)[].

Other Uses

A hard wood of good quality that is exploited commercially[].

Propagation

The seed is best sown as soon as it is ripe in individual deep pots in a cold frame[]. You need to protect it from mice, birds, squirrels etc. The seed usually germinates in late winter or the spring. Plant out the seedlings into their permanent positions in early summer and give some protection from the cold for their first winter or two.
The seed can also be stored in cool moist conditions (such s the salad compartment of a fridge) over the winter and sown in early spring but it may then require a period of cold stratification before it will germinate[, , ].