From acorns to oaks
Nebraska Statewide Arboretum
To grow plants from seeds, you don’t need to go to the local nursery and buy a colorful packet. A little knowledge can create a rewarding do-it-yourself experience.
One plant that is relatively easy to start from seed is the oak. Acorns mature in early fall in Nebraska. You can tell the seed is ripe when the outside changes from green to yellow, brown or black and the caps can be easily removed. Acorns can then be plucked off the tree or picked up from the ground soon after falling. It’s important to note that acorns left on the ground for several days begin to dry out and become a food source for insects and wildlife.
After collection, acorns should be soaked in water overnight to rehydrate any dry seeds. Floating acorns, along with any other debris, should be skimmed off the top. The remaining sunken acorns are the most viable and pest-free.
Next, lay out the healthy acorns in a single layer on a clean surface and allow seeds to dry about 30 minutes to reduce molding. Acorns then should be transferred to a sealable plastic bag and placed in a refrigerator set at 37 degrees Fahrenheit (F). This cold storage – called stratification – mimics the acorns’ need to go through a winter in order to successfully germinate. Most acorns need at least 60 days of stratification (only white oaks don’t require this). After stratification, they can remain in the refrigerator until warmer weather permits outside sowing; or you can sow them inside if you have access to a greenhouse or other area with temperatures of 86 degrees F during the day, and 68 degrees F at night. Sixteen hours of sunlight or artificial light is also necessary.
When planting the acorns, select a pot at least 5 inches deep to accommodate the taproot. Fill the pot with a general purpose potting soil, leaving 2 inches at the top. Place the acorn on its side in the pot and cover with 1 inch of potting soil. Water the acorn until moderately moist, with a few drips coming out the bottom of the pot, and continue watering every few days until it has sprouted and can be planted outside after the danger of frost has passed.
Select a sunny location with enough room for the tree to grow. Dig a hole about 1 foot wide and the same depth as the pot. Plant the seedling slightly higher than it sits in the pot. Support the seedling while carefully adding soil around the roots using moderate compaction. Add 2-3 inches of wood chips 18 inches around the tree, keeping the mulch away from the stem. Water the seedling well, and do so every week in its first year if rainfall is less than 1 inch a week. A wire cage is usually a good idea to protect a young seedling from things like wildlife and lawnmowers.
– Oak is the common name for the tree. It goes by other names in other parts of the world. Scientifically, it’s in the Quercus genus.
– There are about 500 species of oaks in the world. About 70 of these are native to the United States, with seven native to Nebraska.
– Quercus is the largest genus of hardwood trees and shrubs native to the United States. This includes both deciduous and evergreen species.
– Oaks native in Nebraska are: white oak (Quercus alba), bur oak (Quercus macrocarpa), blackjack oak (Quercus marilandica), chinkapin oak (Quercus muehlenbergii), dwarf chinkapin oak (Quercus prinoides), red oak (Quercus rubra) and black oak (Quercus velutina).
– Oaks have many valuable uses including: furniture, construction timber, wildlife habitat and food, watershed protection and ornamental plantings.
– Oaks have deep growing roots called taproots. Taproots help the tree withstand drought by reaching water far below the surface of the ground.