The mighty oak begins life as an acorn. Generally, by the following spring, a young seedling will begin to poke through the soil. If a young oak seedling is left in a native location for two years or more, after growing from an acorn, it may be too large to replant. Typically an oak tree will send down a taproot that is approximately 2/3 the size of the upper trunk. In other words, an 18-inch high oak seedling may have a taproot that reaches to 12 inches deep. Cutting the taproot will kill the young oak tree seedling.
Plant the oak seedlings between late fall and early spring while the young trees are still dormant. Dormant oak seedlings will not have any leaves on the limbs.
Dig the transplant or replanting hole two times to three times the size of the oak seedling's root ball. According to the University of California, using a mechanical auger to dig 1 foot to 2 feet deeper than the container root ball will encourage deeper root growth. Deep root growth is essential for a young oak tree. A rock bar may be used in place of a mechanical auger to dig the deeper hole.
Backfill around the oak seedling using the native soil from the transplant hole. Use you hands to gently tamp the soil around the roots of the seedling. Keep the soil line from the container-grown tree equal to that of the transplant location.
Make a soil ring that is 18 inches to 24 inches in diameter around the trunk of the young tree, and approximately 3 inches high. The soil ring will aid in retaining water around the young tree, and guide the collected water to the roots.
Add approximately 5 gallons to 10 gallons of water to the interior of the soil ring. The water will remove any air from around the oak seedling's roots.