Knock the nuts from the tree when the green hulls begin to split and the packing tissue between and around the kernel halves has just started to turn brown.
Remove the hulls as soon as you can. There are several ways to remove the hulls: use a knife, stomp and roll the nuts with your foot, roll over them with the car tire, between two boards, or work them over a rough screen to loosen and remove the hulls. If the hulls stick tightly to the shells, moisten them and cover with a moist tarp or burlap sheet for several days to loosen. Particularly with black walnuts, but also with the others, wear gloves when handling the hulls to avoid staining your hands.
Wash the nuts to remove clinging fibers, discard any floaters. (My first big harvest of butternuts and heartnuts was 90% floaters, we cleaned them up anyway, they were all blanks!)
Spread the nuts in thin layers on the floor or on wire mesh trays in a warm well-ventilated area out of direct sun to cure that is pest proof (mice, squirrels, jay birds, etc.). Curing will take several weeks; the nuts will tend to rattle in the shell when they are done. Store the nuts in their shell in a cool, dry, well-ventilated location for several months. Shelled nuts may be frozen for up to a year. We offer the Kenkel Nut Cracker #T360 for hard shelled Black Walnuts, Butternuts and Heartnuts.