When done properly, pruning roots might help stimulate a tree growth and drive it into bloom. It can also boost the quality of the harvest on some fruit trees. However, not all trees manage root pruning well. Stick to fruit trees and ornamentals like dogwood (Cornus florida), that rises in U.S. Department of Agriculture plant hardiness zones 5 through 9. Pruning tree roots can have catastrophic impacts on the health of the tree, so plan carefully prior to cutting the roots.
Gauge the width of the trunk at a height of about halfway in the ground to the first branch. Multiply that diameter by 5 and that number is how far out from the tree you should prune the roots. For example, if the tree contains a 20-inch trunk diameter, then measure out 100 inches in the trunk base.
Wait until the tree is ready for root pruning. In ornamental and fruit trees, this is often as soon as the existing blooms become well established and the tree is healthy enough to resist root pruning. This can cause some blooms to drop, but many will reappear as the tree goes to high gear to repair the root system. For young hardwoods which are not growing as quickly as you think they need to, wait to prune until mid-summer once the tree is fully leafed out; the leaves might help supply nutrients to support the tree while the root system redevelops.
Use a shovel to dig the dirt to find the root locations at the correct distance in the tree. Look for big roots extending out from the trunk base and follow a straight line out from the trunk for the very best results, but hidden origins can grow in almost any way. Most roots remain within 12 inches of the surface, so there is no need to dig deeper than that when you’re looking for roots.
Dig a hole big a few inches wider than the origin to provide you with room to work.
Shut the blades of big branch loppers across the root and compress sharply to cut through the origin. Repeat if required to chop all of the way through the origin. Massive loppers can usually cut roots around 3 inches in diameter, which is about the maximum size you should prune; cutting larger roots can result in an unstable tree which starts to fall or lean.
Prune a few roots on all sides of the tree, spacing them out evenly. Pruning on one side just can shock the tree, causing the side to begin to perish. Cutting the ideal number of roots can help improve the tree fruit or bloom production, but cutting a lot of can kill the tree. According to the Michigan State University Extension office, then you can prune around 60 percent of the roots to help promote bloom and fruit production.
Replace the dirt above the cut root. Don’t deal with the root using a product designed to encourage healing, as the root should begin to sprout out in the cut.
Water the tree with a deep, bald watering daily for about two weeks to make it easier for your tree to recover from the root pruning and give the tree that the moisture it needs to grow blooms and fruit.