The crown of walnut is huge and majestic, with dense branches and leaves, covered with green shade and clean gray trunk, which is also quite pleasant. This is a good shade tree.
Both single planting and cluster planting are suitable for grassland or garden space.
Because of the volatile smell of flowers, fruits and leaves, it has the health care function of sterilization and insecticidal, and can also be planted in scenic spots in pieces and forests.
Walnut is a deciduous tree with a height of 30m and a DBH1m.
The crown is broadly ovoid to oblate.
When the bark is old, it is gray and deep vertically.
1 annual branches are green, glabrous or nearly glabrous.
5-9 leaflets, ovoid, ovoid to obovate, 6-14cm long, obtuse or oblique at the base, entire, the leaves on young trees and budding branches are serrated, the lateral veins are often lower than 15 pairs, the surface is smooth, there are tufts of hairs on the axils of dorsal veins, and there are oil glands on the back of young leaves.
Male flowers are inflorescences, born on the side of branches last year. Perianth 6-lobed, female flower 1 ~ 3 (5) into a terminal spike, perianth 4-lobed.
Drupe is spherical, 4 ~ 5 cm in diameter, subglobose, blunt at the top, with irregular shallow grooves and 2 longitudinal ridges.
The flowering period is April-May, and the fruit ripens in September 9- 10/October165438+1October.
Walnut likes light, warm and cool climate, and is resistant to dry and cold, but not to damp and heat.
It can grow normally under the climatic conditions of annual average temperature of 8 ~ 14℃, extreme minimum temperature above -25℃ and annual precipitation of 400 ~ 1200mm.
I like deep, fertile, moist, slightly acidic to slightly alkaline soil with good drainage, which will not grow well in barren, saline-alkali, strong acid and high groundwater level.
Deep-rooted, with thick fleshy straight roots, it is afraid of flooding.
The growth is still fast, the height of 5-year-old trees is 3 ~ 4 meters, and the height of 20-year-old trees is about 12 meters.
Generally, the fruit begins to bear fruit at the age of 6-8, and reaches the full fruit stage at the age of 20-30.
Walnut has a strong apical advantage in its infancy, but its dryness will soon change from strong to weak. After entering the mature stage, its terminal bud is a mixed bud, so it is mostly in the form of axial branches.
The plastic path in the garden takes the shape of a leaderless trunk.
Walnut branches are mostly horizontal and easy to droop after middle age, so the height of trunk should be at least 2 meters when setting, and the plastic belt should be 2 ~ 2.5 meters.
Trunk is difficult to maintain, so it is necessary to maintain the growth of trunk at seedling stage. When the height of the trunk is more than 2m, cut off the auxiliary branches below 1.3m, and keep 2 ~ 3 main branches within1.3 ~ 2.5m without cutting off the trunk.
After 2 ~ 3 years, add 2 ~ 3 secondary branches and let them grow naturally.
After the canopy is closed, more than three skeleton branches with branching points of more than 2 meters are screened out from the remaining main branches and secondary main branches, the redundant branches are thinned out, and the extension of the middle trunk is cut off to form a leaderless trunk form, and the culture process takes 5-6 years.
Walnut has obvious layering, so it is not suitable to cut more garden trees. Usually only miscellaneous branches can be sorted out (long branches need to be thinned).
Walnut, as a fruit tree, has the habit of mixing buds at the top of branches, so the fruiting branches are generally not shortened. Usually, only dense branches and dead branches are thinned, but it is feasible to shorten some necessary weak branches.
In the garden, as a garden tree, walnuts need not be so particular.
Because walnut sap flows early and vigorously, it is not pruned during dormancy to avoid excessive bleeding and damage to the tree.
Generally, pruning is usually carried out after fruit picking and before defoliation.
When the tree is old and decayed, it needs to be cut down again to promote its rejuvenation and renewal.
However, attention should be paid to sawing off the main branches in batches year by year, otherwise it will lead to fruitless consequences for many years.