Prepare containers for the black walnut seeds after the cold stratification period has ended. Plant walnuts 1 to 2 inches deep. Steps for Refrigerator Stratification Step 1: Add Seeds. Step 2: Monitor Moisture. You can store them in the … The cold-moist requirement can be met by planting the nuts in the ground in fall. The cold-moist requirement can also be accomplished through a process called stratification. Keep your medium moist for the entire stratification period. Stratify walnut seeds by placing them in a moist mixture of sand and peat moss and then storing them in a cool location. Walnuts can be stratified by placing the nuts in a moist mixture of sand and peat moss and then storing them in a cool location. Fill 1-gallon nursery containers with a mixture of equal parts compost, potting soil …