Thinning an Oak Tree
Oak trees offer majestic splendor to the landscape and spectacular shade to your yard. Plus, they provide acorns annually, a treat for critters around your property. There are many varieties of oak trees, but most are fast growers, averaging a development rate of about one foot per year. A mature oak tree can reach 80-150 feet in height and spread over nine feet wide. With that kind of growth, large branches develop.
In heavy winds or under the weight of snow, those branches can break off the tree, potentially delivering a devastating impact to anything below. For this reason, it’s important to keep dead wood and unhealthy branches thinned. General pruning also facilitates healthy growth and handsome structure.
Step 1 - Choose Your Timing
Thinning any deciduous tree is best done in winter, when the sap is at the roots. Thinning of oak trees can also be done in midsummer after a growth spurt, once all the new leaves are producing food. It's not a great idea to prune in the spring or fall. Remember that removing a branch leaves a wound that must heal, so you don’t want to prune when the tree is putting its energy into actively growing.
Step 2 - Follow Safety Protocol
Oak trees create heavy branches, and you may be working high in the air, so use safety protocols as you work—wear safety glasses, a hard hat, and good quality leather gloves for protection. Use a ladder or climbing harness and try to remain level to the branch you’re working on rather than below it. When managing branches high up or small branches at a lower level, use a handsaw or pruning saw rather than a chainsaw.
Step 3 - Know the Proper Reasons to Thin Oak Trees
Most oak trees will grow and thrive with very little maintenance. In fact, cutting branches when not necessary will cause more harm than good so it’s important to create a plan that will meet your needs and benefit the tree. Oak tree foliage is thinned out to prevent obstruction of electrical wires, to allow light penetration into gardens and lawns, and to redirect the tree's growth vertically.
Focus on dead, diseased, or weak branches that can infect other parts of the tree. Also remove branches growing up into the center canopy of the tree—you want the center to remain open for proper airflow. In addition, cut branches that overlap each other, block driveways, threaten buildings, or are growing in a downward direction.
Step 4 - Thin the Crown
Look for branches in the crown that are causing crowding. Crown thinning maintains the natural direction of branch and limb growth, permits sunlight to pass, reduces wind resistance, and slows the oak tree's growth rate.
Step 5 - Thin the Bottom
Crown lifting removes the branches nearest the ground to ensure minimum ground clearance for pedestrians and tall vehicles such as buses, RVs, and freight trailers.
Step 6 - Make Proper Cuts
Don’t cut flush with the trunk. Instead cut outside the bark of the trunk so the existing bark can naturally grow over the wound left from the branch removal. This means you will leave about an inch of the branch attached to the tree.
Remove small branches early on when they are less than two inches in diameter. For larger branches, remove no more than ⅓ of a living branch. Cutting large branches back too harshly can stress the entire tree and cause it to die.
For longer branches, cut off in sections. If you attempt to cut the branch all at once, the weight of the branch can cause a tear rather than a clean cut, damaging the trunk of the tree. To properly remove a branch, make a cut on the underside of the branch about ¼ of the thickness, a few feet from the trunk of the tree. Then move to the top of the same branch to complete the cut. Removing the majority of the branch in this way takes the weight off and allows you to make a final, clean cut closer to the trunk.
Warning: If your tree branches are near power lines, call the electric company to handle the task to avoid the risk of electrocution. Also, if you are removing a large branch, use a rope to lower it once it is cut from the tree.