The Black walnut, a tree primarily native to the Midwest and east central United States, is not only prized for its shade and beauty, but also for its wood and fruit.
The Black walnut was first introduced into Europe in 1629. This large deciduous tree can grow as high as 98–130 ft. You can distinguish this tree by its grey-black bark which is deeply furrowed.
The Black walnut is favored in the Midwest due to its resistance to frost as opposed to the Persian walnut or English walnut. The Black walnut thrives in warm regions that are fertile and have lowland soils with a high water table. This tree flourishes along the Mississippi river areas, including Missouri, where 65% of black walnuts are harvested for commercial use. The nutmeats are used as an ingredient in food while the shell is utilized commercially for abrasive cleaning, cosmetics, oil well drilling and water filtration.
The wood is valued for its use in making furniture, rifle stocks and sometimes flooring. The dark-colored heartwood of the Black walnut is heavy and strong, easy to split, and easy to work.
Throughout time, the Black walnut tree and its nuts have been utilized by people, meeting many of their needs. In pioneer days, nuts not only provided food but the shells were used to dye cloth. The wood was used for anything and everything, including making gun stocks. Later, shells of the Black walnut were used during World War II in gas mask filters. Shells were also used to clean jet engines and to activate carbon.
When planting your Black walnut, be sure to keep it away from your garden. A chemical found in the tree’s roots, leaves, trunk, and nut husks can inhibit the growth of: tomatoes, potatoes, alfalfa, blackberry, domestic grape, lilac, hydrangea, chrysanthemum, paper birch, red (Norway) pine, Scotch pine, hackberry, basswood, apple, and other plants grown too close to a walnut tree. This effect remains long after a walnut tree has been removed.
Also, do not try to grow walnut where soils are poorly drained or wet during the growing season or where flooding or ice damage is frequent. Examine soil survey maps and written soil descriptions to identify soil types suitable for walnut. When walnut or other trees are not present to allow you to judge site quality, dig several pits or cores to evaluate soil depth, texture, drainage, and fertility.
Walnut grows well on river terraces and hillside benches, and in coves in hilly terrain facing north or east. It will not grow well on steep slopes facing south or west—such sites are too hot and dry.
Walnut trees begin producing nuts when they are about 10 years old, but the best nut production begins when trees are 30 years old. Good nut crops occur in about two out of five years.
Allow 200 to 300 square feet of growing space around each tree at the time of establishment. Gradually thin to about half this density as trees mature. Keep other trees and shrubs from invading. Sod reduces nut production, but also reduces soil erosion and may discourage other plants from invading that would make nut collection difficult.
The Black walnut tree is an amazing piece of nature. Although its post-life uses are many, the tree itself can make a lovely addition to any piece of land.
About the Author: Andrew Johnson is the owner of Central Texas Tree Care, a leading provider of Austin tree services in Central Texas. Certified ISA Austin arborist services including: tree trimming, tree removal, tree care and stump removal. For more information on Austin tree service please visit https://www.centraltexastreecare.com.