The black walnut, scientifically known as Juglans nigra, is prized for its beautiful hard wood and tasty nuts. The Thomas black walnut, scientifically known as Juglas nigra, Thomas, is considered the American walnut as opposed to its cousin, the Carpathian or English walnut. Some varieties of black walnuts have been known to live as long 200 years, though the Thomas variety generally lives between 70 and 100 years.
Black walnut trees reach from 70 to 150 feet tall. Their trunks can measure 2 to 4 feet across. When grown in the open, it is more short-stemmed with a wider reaching crown than when grown in a hardwood forest. The bark is identified by its rich, dark brown color and deeply creviced nature. Before nuts are produced, identify the tree by diagonally cutting a twig and examining the pith for its dark-brown honeycombed appearance. The Thomas black walnut was the first chosen for use because of its nut production. It has been propagated since 1881 for that purpose.
Where Does it Grow?
Black walnut trees, including Thomas, grow primarily in the eastern United States. They grow as far west as Kansas toward the Atlantic coast and from Minnesota in the north to Texas in the south. They grow in planting zones 4 through 8, spanning regions with growing seasons from 140 to 280 days, making it a versatile tree.
How to Grow
Like other black walnut trees, Thomas black walnuts need a permanent space of 50 square feet to allow proper root development. They require 25 inches of rain each year or an equivalent source of water. The soil should be fertile, well-drained and at least 30 inches deep. They also need a minimum of 140 days free of frost. They can grow beside streams that flood in the dormant season but not if the soil is not wet during the growing season. Black walnuts in general do not like shade or exposure to strong wind. They won't do well on west- or south-facing steep slopes because they are too hot. Add fertilizer every second or third year.
The black walnut is prized for its tall, straight growth, creating straight-grained wood used for manufacturing furniture and gunstocks. Having been heavily logged, native stands are small and the wood is now used mostly as veneer. The wood of the black walnut shrinks and swells less than any other wood, making it ideal for furniture and building material.
Advantages to Thomas Black Walnuts
If planted in the proper location and well-maintained, the Thomas black walnut is superior in nut production for quality of the nut. Thomas black walnuts also fill more of the shell more consistently than other varieties. Another advantage is that they begin producing nuts earlier than other varieties. Most begin at 10 years and reach optimal production at 30 years old. Thomas black walnuts often begin producing before age 5.