After the regeneration stage, well-stocked oak stands should be thinned at about 10-year intervals in order to concentrate growth on the best trees. If less valuable species have outgrown the oaks, thinnings should start as soon as 10 years after regenerating the new stand. You should select potential crop trees on a spacing of about 15 to 20 feet. Choose crop trees that are desirable species with crowns in or above the main canopy, straight stems, and no signs of severe damage.