Types Of Walnut Trees: A Comprehensive Guide

There are about twenty different species of walnut trees, all belonging to the Juglans genus. Of these, only two types (Black Walnut and English/Persian Walnut) are commonly grown in the United States; however, there are many different varieties among Black Walnuts. These deciduous trees, as well as many other walnut species, are distributed across North and South America, southern Europe, Asia, and the West Indies. In this guide, we’ll explore the major types of walnut trees, their characteristics, and where they are commonly found. Read on to learn more.

A Dozen Top Choices In Walnut Trees

English/Persian Walnut (Juglans Regia)

You may hear English walnut trees referred to as Persian walnut trees. By either name, these trees start their lives with smooth, olive-colored bark, which turns gray and becomes very deeply fissured as the trees mature. These trees can grow up to 65 feet high and have very wide canopies.

English walnuts produce spherical drupes with excellent nuts. The fruits start out green on the tree and then turn nearly black when they fall. They are a primary source of walnuts in North American markets.

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Black Walnut (Juglans Nigra)

Black walnut trees are easily recognized by their deeply furrowed bark. These slow growing, long-lived trees can reach heights of 75 to 130 feet and are typically found in USDA zones 4-9.

Black Walnut trees have large pinnate leaves. Like English walnut trees, they produce spherical green fruits that turn black when ripe. The fallen walnuts produce a distinctive citrus-like odor when crushed.

If Black Walnut trees will grow well in your area, you should consider the various cultivars that are available.

If you want to grow walnut trees for nuts, standard Black Walnut is a good choice but a bit slow to mature. If you want to be able to harvest a nut crop more quickly, look for a cultivar such as Sparrow, Snyder or Kwik Krop.

California Black Walnut (Juglans Californica)

These walnut trees can be small with a single stem or they may be large multi-stemmed shrubs, growing between 20 and 50 feet high in zones 7 to 10.

These trees have thick, dark gray bark lined with deep furrows. Their leaves are pinnate with 12 to 19 elongated leaflets.

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Northern California Black Walnut (Juglans Hindsii)

These trees are quite common in Northern California. They have solitary stems and can grow up to 60 feet high in zones 8-9. They present a distinctive appearance thanks to dark gray bark, leaves with 13 to 21 leaflets, and little hair tufts on the leaves.

Arizona Black Walnut (Juglans Major)

Description: Arizona black walnut trees are small, with the tallest ones reaching heights of 50 feet. They have long stems supporting a spreading crown that may be as large as 65 feet wide.

Features: These trees produce small edible nuts and have gray-brown bark marked with flat-topped ridges. Their leaves are pinnately complex with 9 to 15 leaflets each.

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White or Butternut Walnut (Juglans Cinerea)

Butternut walnut trees have smooth gray bark and are smaller than black walnut trees. They typically attain heights of 60 to 66 feet in zones 3 to 7.

The fruits of the Butternut walnut are oval rather than spherical, and true to their name, they have a buttery flavor. These trees are more companionable and release fewer toxic chemicals into the soil than black walnut trees.

Japanese Walnut (Juglans Ailantifolia)

Japanese walnut trees resemble Butternut trees and also have light gray bark. They are also similar in size and may grow up to 66 feet high.

Their walnuts also have an interesting shape in that they are heart-shaped! The leaves of this tree have 12-17 broad leaflets on each twig.

Andean Walnut (Juglans Neotropica)

Slow-growing Andean walnut trees can reach up to 130 feet and are found in the highlands of Ecuador, Colombia, and Peru. They have prized red-colored, high-quality timber and long oval leaves of up to 15 inches.

Little Walnut (Juglans Microcarpa)

This neat little tree is the very smallest of walnut trees. In fact, Little Walnuts resemble shrubs and grow only about 30 feet high in zones 7-9. The bark of these shrubs may be gray to dark brown bark. The nuts are quite small, and the leaves have 7 to 25 tiny leaflets.

Manchurian Walnut (Juglans Mandshurica)

These trees originate from East Asia and are hardy and cold-resistant, thriving in zones 2-8. Manchurian Walnut is a good choice as a focal point or specimen planting in almost any yard or garden.

These mostly ornamental trees have very attractive, deeply fissured bark and extremely small walnuts. They grow to be about 45 feet high.

Chandler Walnut Tree

This cultivar was created by the University of California and is winter hardy in USDA hardiness zones 4-8. The Chandler walnut tree produces very large thin-shelled nuts with light-colored kernels.

The trees’ semi-upright growth habit and relatively small size (50 feet) make harvesting the walnuts very easy. The thin shelled nuts are easy to crack and clean.

Brazilian Walnut (Juglans Australis)

Brazilian walnut trees are spreading deciduous trees that may attain a width of 75 feet and
produce superb lumber. These trees are naturally found in tropical regions. In North America they may be grown in zones 10 to 12.

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Careful Selection Supports Successful Walnut Tree Growth

It’s easy to see that there are many varieties of walnut trees, and there is bound to be a type that will do well in your climate.

While Black Walnut, Butternut and English Walnut trees are the most common types grown and found in the United States, there are certainly many other possibilities to choose from, as long as you keep the needs of the tree and your intended use of it firmly in mind.

Growing walnuts requires careful consideration of local climate conditions and choosing appropriate cultivars whose flowering and ripening times will coincide with your climate and avoid frost damage.

For more information on growing walnuts in specific regions, contact your local agricultural extension and/or consult local resources and databases.