The black walnut, or Juglans nigra, is a hardy, round nut that is about 2 inches in diameter and rich in omega-3 fatty acids. You can eat the black walnut meats raw or use them in making baked goods. Harvest the black walnuts between early autumn and early winter, when the husks turn a yellowish-green and when pressing on the shell leaves an indentation. Be sure to wear gloves when you're handling the unshelled black walnuts, because the husks contain residues that can stain your fingers. Spread a drop cloth over the area where you'll be hulling and shelling the black walnuts to prevent staining any surfaces. Wear eye protection and an apron.
Crack the black walnut hull by tapping the two ends of the nut with a hammer or small mallet. Pry open and remove the hull.
Place the hulled black walnuts in a colander. Rinse them thoroughly outdoors using a garden hose to prevent stains in and around your sink.
Filter any the black walnuts that may have insect damage by placing them in a bowl filled with water. Discard any walnuts that float to the water's surface.
Cure the hulled, unshelled black walnuts by spreading them on a wire mesh surface no more than two or three walnuts deep. Allow the black walnuts to cure in a dry, cool place away from direct sunlight for about two weeks.
Store the unshelled black walnuts in cloth bags or wire-mesh baskets in a cool, well-ventilated area that's away from direct sunlight with about 70 percent humidity.
Prepare the black walnuts for shelling by soaking them in hot water in a large bowl for 24 hours. Drain away the water and refill the bowl with fresh hot water, soaking the black walnuts for two more hours.
Shell the black walnuts using a nutcracker, preferably one made specifically for black walnuts. Remove the nut meats carefully, using a nutpick if necessary.
Store your black walnut meats in an airtight container or plastic bag in the refrigerator for up to nine months, or in the freezer for up to two years.
Store the nutmeats at room temperature for up to three weeks by first baking them for 10 to 15 minutes in an oven set at 215 degrees Fahrenheit. Cool and store the nutmeats in an airtight container.