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 mulch. This is a trees’ natural environment that creates a healthy fibrous root system that gathers water and natural nutrients necessary for good tree health. Now enter the lawn. Thick grass is a healthy tree’s biggest competitor for moisture and natural nutrients. Fall leaves are removed as to not smother the grass. Herbicides are applied annually to control lawn weeds. Many trees are planted in new subdivisions that have had the topsoil removed and the clay is a plenty. Trees growing under these conditions grow under constant stress, drastically reducing the longevity of your trees.
Since homes need both trees and lawns, what’s the best way to make these two more compatible? By a process referred to as vertical mulching, a time tested method of overcoming the stresses trees face in the unnatural environment most grow under. It creates columns of rich “top soil” 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 thousands of new feeder roots flourishing there. Vertical mulching also provides the perfect opportunity to fertilize your trees. Many trees, especially oaks and maples, have been brought back from the brink of death from proper vertical mulching. Do not expect instant results. Trees slowly go into decline and slowly return to health after vertical mulching. It might be two years or more before the foliage thickens and the tree gets its rich leaf color back.
Vertical mulching is the process of making many holes in the soil of the root zone of a particular tree with the purpose of creating many entryways for air, moisture, and nutrients to reach the roots of a given tree. This process improves the overall health and vigor of any tree. To properly vertical mulch, you will need an electric or gasoline powered drill and a 2 to 3” diameter auger. This equipment is available from any tool rental.
Starting 8 ft. away from the trunk (no feeder roots there,) drill holes on 3 ft. centers 15” deep in all directions. Discard the soil that is removed from the hole. The holes should cover at least the area shaded by your tree at high noon. Feeder roots actually grow a minimum of 25% beyond this area. If this area includes your neighbor’s yard get permission to drill on their property.
Back fill the holes half way with a mixture of 50% peat moss and 50% course sand or use straight pea gravel. Measure the diameter of the tree at chest height. You want to apply 2 lbs. of 10-10-10 or 10-6-4 fertilizer for every inch of tree diameter. Distribute this fertilizer evenly in the holes you’ve drilled. Then continue to back fill until the holes are filled. Late fall is the best time to vertical mulch with early spring the second, but anytime of the year you do it will have your tree (trees) saying thanks.
A Word of Caution
Be careful where you drill if you have an underground sprinkler system. In Ohio, call the Ohio utilities protection services (1-800-362-2764) to mark any other underground systems. There is no charge for this service.