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Woody > Juglans > Juglans regia > Juglans regia

Juglans regia

Common, English or Persian Walnut

Origin:  Central Asia, they were brought to Europe by the Romans and made their way to North America under the passage of European settlers.
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Juglans regia is known as the English, Persian, or Common Walnut. This medium sized deciduous should not be planted near a patio, walkway or frequent travel area because of the mass dropping of golf ball sized fruit in autumn. It may be considered a problematic species because of the juglone produced by the tree limiting what can be grown under its canopy, thus plant selection is critical.

Michael Pascoe, NDP., ODH., CLT., MSc. (Plant Conservation)


Tree (deciduous)
USDA Hardiness Zone
Canadian Hardiness Zone
Temperature (°C)
Temperature (°F)
18-25 m
12-20 m
Description and Growing Information
Flowering Period
General Description
This medium sized deciduous tree has alternate, medium to dark green pinnately compound leaves. The leaflets vary in shape from elliptic to obovate. The terminal buds are brownish and 5-8 mm long. The bark is smooth, silver-grey with vast flat ridges.
A large specimen, it produces a beautiful silhouette in the winter and can be a fine-looking sight in the summer. The leaves, roots, and foliage discharge a substance called juglone that can stain or change the colour of cement and other surfaces. Some plants cannot tolerate juglone and will not grow near the tree. The tree drops a large amount of fruit and should not be planted near patios, walkways, or any area that is highly traveled: it is best suited to community gardens or open areas such as parks or estates.
The Common Walnut prefers a pH of 6-7.5 in dry, deep, light loamy, yet well drained soil and does poorly in wet areas. It requires full sun.
Large, rounded crown.
ID Characteristic
The pinnate leaves only have 5-9 leaflets and are wider than the Black Walnut. The male flowers are green dropping catkins that are 5-10 cm long and the female flowers produce a golf ball sized green husk with a brown seed inside. The husk and seed fall together as one in autumn.
Many pests are associated with the Common Walnut such as, codling moth, walnut husk fly larva (ruins the fruit), and walnut blight. Rodents can be a problem with young trees and seedlings because they occasionally eat the bark.
The Common Walnut is found in drier areas of south west Asia to the Himalayas and southeast Europe on mountain slopes at 500-1800 m. Generally there are no understory trees because of the juglone produced, so they are often found as solitary groups.
Bark/Stem Description
The silver-grey bark is smooth with large flat ridges. The herein bark is different from other species. The stems are olive brown when undeveloped, and then turn more gray as they become branches.
Flower/Leaf Bud Description
The terminal buds are brown, 2-3 fold larger than lateral approximately 5-8 mm long with scales barely overlapping.
Leaf Description
The glabrous medium to dark green, sessile leaflets are alternately arranged on the pinnately compound leaves. There are 5-9 leaflets on each leaf, obscurley serrulate on young plants, t 5-12 cm long and vary from elliptic to obovate, while the leaf is about 25-35 cm long. The petiole is 5-7 cm long, rachis and glabrescent.
Flower Description
The male flower spike is a pendulous catkin that is 5-10 cm long with 6-30 stamens. The female flower is composed of 2-3 carpels surrounded by 4 'perianth' leaves distichously arranged.
Fruit Description
The nut is subglobose, olive green, golf ball sized with a glabrous husk. They are irregular dehiscent with an edible nut inside which is about 5 cm in diameter, the wrinkled nuts are thick shelled (except in commercial cultivars) but easily removed from the husk. The nuts are typically held in clusters of 2-3. California produces most of North America’s edible Walnuts.
Colour Description
In autumn the Common Walnut's foliage colour varies from green, yellow, to brown. Throughout the spring and summer the leaves are a medium to dark green. The leaves are quite glossy. The bark is grey-silver in colour yet the stems are an olive-brown when young turning grey as they mature. The terminal buds are brown.
Texture Description
Medium in the spring and summer in the autumn the female flowers produce flowers are they grab your attention.
Notable Specimens
Clay Centre, Ohio, United States of America.
Stratify seed at 4°C for 90 days, sow seeds in individual long pots since the seedlings will produce a long taproot. Commercial cultivars are often grafted onto Juglans nigra.
Nelson, Martin. "Plant Profile." United States Department of Agriculture. N.p., 20 2012. Web. 22 Nov. 2012. Capon, Brian. Botany for Gardeners. 3rd ed. China: Timber Press, Inc., 2010. Print.