How to grow your own native oak trees
T he end of summer begins the season of acorn gathering in California. It was once so important to Native Americans the whole year pivoted around the gathering and processing of these nuts. Gathering isn’t just scooping acorns into a basket, it is the tedious inspection of the ground for only the most perfect ones. The rest were left for wildlife and to regenerate the trees.
These seeds of the oak are large and easy to identify. Endless groves of oaks include Quercus agrifolia on the coast to Quercus lobata in the valleys and Quercus kelloggii in the higher elevations. These as well as countless other, less defined, sometimes scrub species fill the rest of our wild land plant communities. As a result we are awash in acorns this year after so much rain, and each one of them is the genesis of a new tree.
Growing oaks from acorns is a great way to make new trees at no cost. Growing with acorns gathered from local trees ensures your trees are best adapted to the conditions of your immediate microclimate. Its progeny will share the same traits for maximized resistance to drought, pests and disease. Acorns of the same species obtained elsewhere will grow well, but they may not be as vigorous without the micro adaptations.
By the time an acorn sprouts its first leaf, the tap root is two feet deep. This is an important trait for anchorage and access to deep moisture before that first long, dry summer. When acorns are planted in containers, the tap root hits the bottom in just weeks, then takes a sharp turn. If the acorn is planted directly into outdoor soil, the tap root is free to go deep from the start to ensure maximum drought resistance.
To grow your own native oaks, gather only perfect acorns in the fall right after they are shed by a local oak tree. Freshness is key. Discard any that are small, light weight, discolored, cracks or holes in the shell. Tiny worm holes made by maggots not only consume the seed inside, they later exit to infest the rest of the stored acorn crop.
Place the selected acorns in a plastic container and store in the refrigerator for the winter to simulate dormancy. Extend this early dormant storage as required for your local gardening timeline. Be prepared to plant the acorns out in the late winter where it’s warm. Wait for early spring to sow when temperatures outdoors begin to thaw in higher elevations or where ground freezes.
About a month before sowing time in your area, remove the acorns from the reefer and put into a one gallon nursery pot. You can add sand to retain moisture or simply leave them as is where it is damp enough. Place the pot outdoors where it is exposed to sun and rain. Check the acorns every few days for hairline cracks that indicate activity has begun.
A cracked acorn is ready to plant in ground immediately to avoid dehydration. Plant the acorn exactly where you want the tree to live. Set it on its side at the bottom of a narrow hole about six inches deep. A bulb planting tool is perfect for planting a whole grove of trees in hard soil.
Mark the place where the acorn was planted with spray paint or a stake so the emerging sprout isn’t trampled. Protect the new shoot from deer and other wildlife with a two foot tall by 6 to 8 inch diameter tube of chicken wire staked into place.
Summer’s end begins the season of acorn gathering. It is a bonanza for all who wish to improve the environment or landscape the yard with native trees. Sell or donate your cracked acorns to fund raisers and Master Gardener plant sales. And though we may no longer be alive when the acorns become mighty oaks, another generation will indeed be there to appreciate the shade.