Environment Planet Earth Harvesting a Black Walnut Crop By Steve Nix Steve Nix Writer University of Georgia Steve Nix is a member of the Society of American Foresters and a former forest resources analyst for the state of Alabama. Learn about our editorial process Updated January 5, 2020 Hans / Pixabay Share Twitter Pinterest Email Planet Earth Outdoors Weather Conservation Learn all the steps for identifying, gathering, and harvesting black walnuts. 1 of 8 Black Walnut Trees Boxed black walnuts under tree. ThoughtCo / Steve Nix Here is a small property near Franklin in western North Carolina which has five healthy, mature black walnut trees. Their potential production is presently over 3,000 walnuts and their age is over 50 years each. These black walnut trees are of natural origin, very much alive and living near a creek ecology with perfect growing conditions and extra fertilization from the yard. There are young trees to take their place and old trees that are losing their battle for life and productivity. Still, there are black walnuts in the queue through the lifetime of children. 2 of 8 Harvesting Black Walnuts Jean-Pol GRANDMONT / Wikimedia Commons / CC BY 2.5 Black walnuts in the husk are about two inches in diameter and shaped like small basketballs. The trees can be identified by their large compound leaves, alternately arranged on the branches. Each leaf has 15 to 23 leaflets and the terminal leaflet is often missing. The nuts grow in clusters of two to five at the end of branches and ripen in autumn into a fruit with a brownish-green, semi-fleshy husk and a brown, corrugated nut. The whole fruit, including the husk, falls in September and October in the eastern United States. The actual seed is relatively small and very hard. 3 of 8 Just Dropped Black walnuts before husking. ThoughtCo / Steve Nix You should allow black walnuts to ripen on the tree and drop naturally, or you can shake smaller trees. Do not pick a black walnut from the tree. After collection, you must remove the husk and cure the nuts for the best flavor. Air-drying works as a curing method if the nuts are well-protected from predators. There are often worms inside the husks, larvae of the husk fly. These insects seldom damage the nut inside the hard shell. The black walnut produces a substance that is toxic, or "allelopathic," to other plants called juglone. Tomatoes and coniferous trees are especially sensitive, so take care with husk and seed disposal. Do not put them in compost. This mild toxin helps the tree keep other vegetation from competing for valuable nutrients and moisture. 4 of 8 Collecting Black Walnut in Husks Field boxed black walnuts. ThoughtCo / Steve Nix As a black walnut fruit ripens, the husk changes from solid green to yellowish-green to dark brown. Remember that you are trying to harvest the ripe nuts directly under the tree ahead of rodents and squirrels. For most large trees, the nuts are too difficult to reach and can only be practically collected after they fall from the tree. Husks must be removed before you store black walnuts. They're easier to remove before the green husk turns into a hard, black seed cover. Don't pile walnuts in husks for long periods of time or let the husks deteriorate. Aging walnut husk's juices can penetrate the shell, discolor the nutmeat, and give the nut an undesirable flavor. Husk them as soon as possible after they drop. 5 of 8 Husking Dehusking a black walnut. ThoughtCo / Steve Nix Rolling the black walnut underfoot on a hard surface, such as a paved driveway is one way to husk. You can also distribute the unhusked walnut on a driveway that won't show stain while slowly rolling over them with an automobile. Commercial huskers use a car tire rotating against a metal mesh. Some take a thick plywood board and drill a nut-sized hole in it (from one to two inches in diameter) and smash the nut through using a hammer. The nut goes through and the husk remains behind. To keep the husk juices from splattering, a board or canvas scrap may be used to cover the nut before hammering. After the husks are removed, the nuts should be stored in a dry place for at least two weeks to cure. Traditionally, they are hung up in bags or baskets to provide better air circulation and prevent mold. 6 of 8 Husked Black Walnut The husked black walnut. ThoughtCo / Steve Nix Walnut juice leaves a dark stain on hands, so if you are concerned about this, wear gloves or use tongs when handling newly unhusked and husked walnuts. Put the husked nuts in a bucket and spray them forcefully with a garden hose to remove the husk residue. Then allow them to dry in the sun at a location that is not accessible to predators. Two pounds of unshelled natural black walnuts will yield about a cupful of nut meats. The shells are hard to crack when you want to extract whole nut halves. If done incorrectly, you often produce a lot of pieces. 7 of 8 Shelling A collection of walnuts. ThoughtCo / Steve Nix The nut and hulls of black walnut serve many purposes. In addition to our personal culinary delight, kernels provide valuable food for wildlife. The black walnut has a much stronger flavor than an English walnut. That strong flavor makes it a desirable nut for baking, in ice cream, or used as a topping. The shell of black walnut is one of the most difficult shells to crack and takes slowly applied pressure against the seam to get larger "nut meat" pieces. There are commercial nutcrackers available, but a slowly tightened vice seems to be effective. The ground-up shells are used in multiple products. Manufacturers use shells to deburr precision gears. Ground shell products are also used to clean jet engines, as additives to drilling mud for oil drilling operations, as filler in dynamite, as a nonslip agent in automobile tires, as an air-pressured propellant to strip paints, as a filtering agent for scrubbers in smokestacks, and as a flour-like carrying agent in various insecticides. 8 of 8 Double Black Walnut A double black walnut. ThoughtCo / Steve Nix As rare as a four-leaf clover, a walnut with double nuts are hard to find. Out of thousands of black walnuts on my trees, only this one was found.