Correctly pruning chinkapins--any of the several species of small American chestnuts--depends upon the purpose of the tree in the home landscape. Chinkapin trees grown for shade could mature from 30 to 60 feet in height but yield none of the sweet chestnuts many growers desire. For fruiting, these trees require pollination partners, and since the species wind-pollinates a grove of trees fares better than a single tree or pair. Close planting makes pruning necessary as trees mature. Single trees require little attention.
Through the growing season watch grafted varieties for branches or sucker shoots forming on the rootstock. With pruning shears clip these off at the trunk or at ground level. Seedling stock may put up multiple shoots from a single root system. Cut out all but the strongest if a single strong trunk is preferred. Chinkapins also thrive as thickets--to produce a shade tree, the side growth must be cut back.
Plantings in chinkapin orchards are often intentionally closely spaced to encourage pollination. Limit pruning of young trees to removing crossed branches and damaged limbs. Cut out one branch in the crossed pair to prevent the limbs from chafing. Use pruning shears or loppers to cut out damaged limbs just below the injury. In winter inspect the trees for dead wood and clip those sections out just above the first healthy tissue.
If maturing trees begin crowding each other, prune to maintain space and eliminate overlapping branches. Use a pruning hook to shorten branches by clipping the leader of the branch back to one of the junctions with the side branches. Severely pruned branches may lose vigor and die back. In winter prune these limbs back to within an inch or two of the trunk. With careful planning, side growth can be encouraged while still maintaining working space between the trees.
Blight damage should be carefully monitored but don't rush to cut out all affected parts of the tree. Chestnut blight does commonly infect chinkapins but the vigor of the trees often overcomes the infection. Chinkapins may put up healthy side shoots even if the blight kills main parts of the tree. Save major pruning work for winter when there's less chance of spreading the infection. Where healthy growth dominates, use pole saws or loppers to cut out failing diseased portions of the tree.
Close plantings of chinkapin seedlings form dense thickets which make excellent wildlife habitat along fences and in hedgerows. Allow the transplanted saplings to become well established before pruning to create hedge stands. In the second or third year when root systems have fully recovered, use limb loppers to cut the saplings back to a few inches above ground level in early spring. Dense clusters of sucker shoots quickly replace the main stem.