Can you explain what “vertical mulching” is and how is it beneficial to our trees?

Well, vertical mulching is the process of making many holes in the soil of the root zone of a tree. These holes, drilled 15 inches deep, by a 1-2” diameter power auger, create entryways for air, moisture and nutrients to reach the roots. Holes are drilled 2 feet apart and should cover, at the very least, the shaded area of your tree at high noon.

Think about it, in a forest, trees are constantly helping to create their own great soil and mulch through their annual leaf drop. Leaves that fell a few years ago are now decomposed into rich topsoil with the freshly fallen leaves acting as the mulch. This natural environment creates a healthy, fibrous root system that gathers water and natural nutrients necessary for good tree health.
But wait, what about the lawn? Did you know that 80% of all U. S. households have private lawns and these lawns collectively account for 18 million acres? Thick grass is a healthy tree’s biggest competitor for moisture and nutrients. Fall leaves are removed as to not smother the grass. Herbicides are applied annually to control weeds. Trees planted in new subdivisions are expected to grow in compacted clay soil. Clay is the type of soil that is leftover after a site’s topsoil has been removed by builders and developers. Trees growing under these adverse conditions are under constant stress that can reduce the longevity of your trees.
Since homes have both trees and lawns, vertical mulching is the best way to make them compatible. Vertical mulching creates columns of rich “topsoil” down past the grass roots and into the soil area where roots can take advantage of them. Several years after vertical mulching, a careful examination of one of the columns would show thousand of new feeder roots flourishing there.
Vertical mulching will also provide the perfect opportunity to fertilize your trees too. Many trees, especially oaks and maples, have been brought back from the brink of death from proper vertical mulching. Do not expect instant results though. Trees slowly decline and will slowly return to health. It could be two years or more before foliage thickens and the tree gets its rich leaf color back.
Late fall is the best time to vertical mulch. Early spring is the next best alternative. But, anytime of year you do it will have your trees saying “thanks, I needed that”