Species Profile: Black Walnut

June 29, 2015

Posted in macstaff

This old Black Walnut tree growing on Sauvie Island in Oregon is one of the largest in the country. Note the man standing at its base.

Black Walnuts are some of the most prized trees grown in North America. Not only is their timber beautiful, strong, and easy to work with, the walnut fruit is popular for healthy snacks and gourmet meals.  The seeds can be pressed to make walnut oil, and the trees’ sprawling limbs make for great climbing and swinging.  A moderately sized Walnut can be 100 feet tall, with a trunk more than 5 feet in diameter. One of the largest known Black Walnuts in North America lives on an island in Oregon. Its trunk is 8 ½ feet across and its limbs spread further than 70 feet in either direction.

Though Walnut trees grow throughout much of the eastern half of the U.S., they are harvested commercially primarily in the Central states. Walnut is also one few species in North America that is planted as well as naturally regenerated, though most commercially planted trees are harvested for fruit rather than lumber. In fact, Walnut makes up only about 2% of available domestic hardwood. Its relatively limited availability combined with its general desirability make it one of the more valuable (and more expensive) domestic woods. This has sometimes led individuals to poach wild Black Walnut trees, and the forestry service has developed a number of methods, including DNA testing, to prosecute those guilty of this crime. For this reason, it is important to purchase Walnut only from reputable dealers who can confirm that it has been harvested legally and responsibly.


Black Walnut heartwood is generally dark to chocolate brown, sometimes with streaks of purple, reddish, or greenish hue. The sapwood, on the other hand, tends to be a fairly light yellow and the contrast, made stark by the trees’ very distinct growth rings, and is often taken advantage of by woodworkers to beautiful effect.

Black Walnut Heartwood and Sapwood
Black Walnut displays a beautiful contrast between heartwood and sapwood

Walnut wood also features a wider variety of figured grain patterns than most any other wood. These patterns, which include curl, crotch, burl, and more, give Walnut a striking character that its mostly straight, even grain would otherwise not display. This unique hardwood also tends to develop a rich patina over time and grows more lustrous, rather than duller, with age.

Because of its natural beauty, Walnut is rarely stained, and it is an excellent candidate for natural oil finishes, which bring out its unique qualities and enrich its hues. Especially in homes with lighter furniture or cabinetry, Walnut will create a beautiful contrast with the other wood in your home.


Though Black Walnut is not among the hardest species, rating 1010 on the Janka Hardness scale, it is considered a very durable wood. It shows an excellent resistance to decay and an appreciable stability, experiencing less seasonal movement than many of its counterparts.

Image credit:
Sauvie Island Oak photo by Ascending the Giants (Own work) [CC BY-SA 3.0] via Wikimedia Commons