How do I germinate acorns?
Acorns should be collected as soon as they fall to the ground. Sound, viable acorns can be separated from damaged or unfilled acorns by placing them in water. Sound acorns will sink. Most floating acorns are not viable and can be discarded.
The acorns of white oak (Quercus alba) and swamp white oak (Quercus bicolor) should be planted in fall. They will germinate immediately after sowing.
Acorns of bur (Quercus macrocarpa), pin (Quercus palustris), and red (Quercus rubra) oaks will not germinate until they have been exposed to cool temperatures and moist conditions for several weeks. Winter weather in Iowa normally provides the necessary conditions to break dormancy. The cold-moist requirement can also be accomplished through a process called stratification. Acorns can be stratified by placing the seeds in a moist mixture of sand and peat moss and then storing them in a cool location. Suitable containers include coffee cans, plastic buckets, and food storage bags. The refrigerator is a good storage location. (Stratification temperatures should be 32 to 41 degrees Fahrenheit.) Acorns of the bur oak require a 30 to 60 day stratification period, while red and pin oak acorns require 30 to 45 days. Acorns of bur, pin, and red oaks can be planted in fall or stratified seed can be sown in spring.
When planting acorns, place the seeds ½ to 1 inch deep. Choose a planting site where the oak seedlings can receive good care for 1 to 2 years before they are transplanted to their permanent location.