Juglans × intermedia
Juglans × quadrangulata (Carrière) Rehder
Juglans × vilmoriniana Lavallée ex Vilm.
Juglans × intermedia is a deciduous tree with a dense, spreading crown; it can grow up to 30 metres tall.
This is the collective name for hybrids between the common walnut, Juglans regia, and the black walnut, Juglans nigra, producing a fruit that is closer to the black walnut. They have arisen in various places, both in Europe and the USA, where the two species are grown together[
]. These hybrids have many of the same uses as their parents, producing edible seeds, a wood of high quality, materials for dyes etc.
A hybrid of garden origin, involving Juglans regia x Juglans nigra, it is not known in the wild.
Not known in the wild.
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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[
A hybrid, J. nigra x J. regia, sometimes cultivated for its edible seed, there are some named varieties[
Seed - raw[
An edible oil is obtained from the seed, it tends to go rancid quickly.
Trees have a dense canopy which tends to reduce plant growth below them.
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 of many 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.)[
All in all species in this genus do not tend to make good companion plants[
This species is a hybrid of the common walnut, Juglans regia, and the black walnut, Juglans nigra. Its uses are similar to its parents, in particular it produces a good quality wood and plenty of material for making dyes.
This species is a hybrid of garden origin and may not breed true from seed.
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[