Germinating black walnut seeds in order to plant them on your landscape is a tricky method of growing the tree, as it is easier to transplant a young seedling. The positive side of starting a black walnut seed from scratch is that it is personally rewarding to grow your own tree, and can also be a way to teach children about gardening and plant growth. The process is simple but does require patience and preparation.
Gather black walnuts that have fallen from black walnut trees throughout September or October. Collect healthy unbroken nuts that squirrels have not already gotten to, and try to find the largest and heaviest ones.
Soak the nuts in a container of room temperature water for about 15 minutes to soften the husk. Wear protective gloves, then remove the nuts one by one from the water. Peel the husk away with your hands and discard. Also get rid of any nuts that float, as these are useless.
Put the black walnuts you removed from the husk in a plastic storage bag with some damp peat moss. Poke several holes in the plastic with a safety pin to provide circulation.
Store the bag in the refrigerator to around 100 days. This mimics the winter season when the seeds need dormancy.
Check the black walnuts often while in the refrigerator for mold or mildew, and keep the peat moss damp with a spray bottle. You don't want the peat moss to be too wet, just moist.
Plant in the spring in a sunny location, putting two nuts in each hole. Cover the black walnut seeds with about 2 inches of loose soil. Water lightly, keeping the soil most until you see sprouts from the seed germinating. Walnuts generally have a germination rate of around 50 percent.