Black Walnut

By Martin Shervey

Black Walnut is one of the Midwest’s most valuable tree species based on price per board foot. Black Walnut can also produce edible nuts along with beauty.

Uses

Black Walnut can be used as food, wildlife attractant, beauty, and lumber, which has been in high demand throughout the world. Walnuts also provide light shade and a bright yellow fall color.

Propagation of Black Walnut

Black Walnut grows throughout the U.S. and Canada. It requires at least 25 inches of precipitation and 140 frost-free days each year. It grows best in soil that is deep, fertile, and moist but well drained. It does not grow well in shallow, dry, sandy, gravelly, or rocky soil. When choosing a site to grow walnut, you should look for a site with good airflow, but not windy, and in the sun.

The first thing in planting Black Walnut trees is to decide what purpose you want to plant them for. There are three main ways of planting Black Walnuts. Each way has a different primary use for the tree.

Lumber Production

If you are planting for timber production, you should plant your trees relatively close together. This encourages the trees to grow straight and self-prune themselves. The trees will grow more slowly, but the growth rings will be closer together; this is desirable in lumber. If you mix in white pines with walnuts, this will help control weeds. They can also be mixed in with red oak and white or green ash. Black Walnut should be thinned out and pruned to increase the quality of lumber at 10 year intervals.

Nut Production

Walnut trees grown for nut production should be grown farther apart to increase crown size and speed of growth. Nut production sites may be grown on poorer quality sites than lumber production because their lumber value is lower. It generally takes about 10 years for trees to produce nuts and best nut production begins at 30 years of age. Sod should be eliminated because it reduces nut production.

Agroforestry

This is when you grow another crop in-between the rows of trees. Plants that can grow by Black Walnuts are Multiflora Rose, Black Raspberry, Morning Glory, Melons, etc. A list is provided at the Ohio State University Extension web site for which plants you can plant and which you cannot.

Black walnut can be planted as either seedlings or nuts. Seedling plantings are more reliable. The stock used should originate no more than 200 miles south or 50 miles north of the planting site.

Planting Nuts

Nuts should be collect from trees with good stem form of large nuts with a high percentage of kernels. They should be collected in September and October after they have fallen from the tree. The husks should be removed immediately and rinsed with water. Then place the nuts a pail of water and discard the nuts that float, for the nuts that sink are more likely to germinate. Walnut requires stratification before they will germinate. Small quantities can be stratified in a refrigerator but large quantities can be stratified by being placed in a pit and covered by 1 to 2 feet of mulch and left over winter. Then plant the nuts in the spring in 1 to 2 inch deep holes, 2 nuts to a hole. After germination, remove the weaker seedling to allow adequate growing space.

Planting Seedlings

This is a more reliable way to start Walnut trees. Seedling size should be ¼ to 3/8-inch in caliper one inch above the root collar. Planting should take place before bud break. Tree shelters help protect seedlings form animal damage.

Seed Harvest

Black Walnut harvest takes place from August through September, in Minnesota. The nuts should be allowed to ripen on the tree. This can be observed when the husk changes from solid green to yellowish green. The nut should have the husks removed before storage because the husk can discolor the nut and ruin the flavor.

The nuts should be checked for injury by placing them in water. Injured nuts will float in the water. Placing the good nuts in a cool, dry, well-ventilated area for two weeks should cure the nuts. The nuts should then be stored in a well-ventilated area at 60 degrees Fahrenheit or less.

Prices

Black Walnut prices for lumber can vary depending on vicinity to a lumber mill. The price of nuts is about $0.6375 an ounce for shelled nuts.

The tree cost can be about $78 for a 2-inch caliper tree to $64 for a 1.5-inch tree.

Reference:

http://www.extension.umn.edu/info-u/nutrition/BJ511/html

http://www.extension.umn.edu/pipermail/mastgar/1998-July/000672.html

http://www.extension.umn.edu/distribution/naturalresources/DD0505.html

http://ohioline.osu.edu/hyg-fact/1000/1148.html