There are four main categories of oak trees including white oak, red oak, burr oak and pin oak. Each type of oak tree grows acorns and sheds them in autumn. Harvesting acorns to start oak trees is the first step in a yearlong process to obtain an oak tree sapling that is ready to transplant into a permanent place in the yard. This process includes transplanting the acorns four times to larger containers, keeping the acorns damp and hardening them off for their final destination.
Place acorns in a plastic sandwich bag with a mixture of 50 percent peat mix or leaf mold and add water to obtain a moist mixture. Choose acorns that are round and swollen for the best results. Harvest acorns off the ground as soon as they fall so they are not rotting.
Close the bag and place in a refrigerator that is 32 to 35 degrees Fahrenheit. Check the bag weekly, and add some water as need be to keep the mixture damp.
Mix potting soil and sphagnum moss in a 50/50 mixture in a bowl. Fill 8 oz. styrofoam cups with the mixture leaving about 1 inch at the top without soil. Use a pencil to pierce the cups in three to four holes near the bottom of the cup for drainage. Plant one acorn per cup so that it lies on its side barely underneath the soil mixture. Water the acorn as often as need be to obtain moist soil and set it on a southern windowsill. This step is best to do from April 15th to the 20th.
Harden off plants about May 15th. The stalk on the acorn tree is 5 to 6 inches tall at this point, and the first set of leaves is spread out. Take the cups outside for a few hours per day to acclimate them to the outdoor elements. Increase the time outside each week over the next two weeks until the oak trees remain outdoors all day and take them inside at night.
Transplant the oaks trees to 16 oz. styrofoam cups in late May in the same manner as the 8 oz cups. Keep trees outside at all times and keep them damp. Transplant the oak trees to 32 oz. styrofoam cups after the second flush of leaves using the same process for soil mixture and holes for drainage.
Transplant the oak trees to a permanent place in the ground in the fall or spring. To plant the trees in spring, leave them inside a garage or other structure and do not allow them to freeze. Make sure to leave enough room for adequate growth and to keep damp. Place a cage or other material around the entire tree to discourage rabbits, birds and deer from eating the young sapling.