Walnut trees are most often purchased and planted as saplings from commercial nurseries. You can plant a walnut and grow a tree from the nut itself if you collect the fallen nuts in late summer or early fall. Plant many more nuts than you think you need. Squirrels find them delicious and will dig up and eat them.
Collect nuts when they fall from the trees in September and October.
Remove the husks. Soften the nuts in a bucket of water. Soak them for 8 to 24 hours until the husk is soft enough to peel off by hand. Wear gloves to protect your hands as the husks contain a dye that stains your skin and clothing.
Place peeled nuts in a bucket of clean water. Discard those that float; they will not germinate. Keep only the nuts that sink to the bottom of the bucket because these will have full kernels and are more likely to germinate.
Stratify nuts in refrigerator. Place the nuts in a plastic bag and put it in the coldest part of your refrigerator--between 34 and 41 degrees Fahrenheit--for 3 to 4 months.
Wait for the ground to thaw enough to dig, usually early spring. Then, plant the stratified nuts. Dig individual holes and plant the nuts 1 to 2 inches deep. Plant them in an open field or nursery garden bed at least 350 feet away from woodland areas to minimize vandalism by squirrels. The nuts will germinate in 4 to 5 weeks.
Transplant the infant seedlings to the desired final location when they are 12 to 18 inches high.