In the past, we have mentioned the hazards of two unfortunate common practices:
1) The ‘pyramid style’ of piling mulch on the base of trees and…
2) Allowing perennial plants, groundcover and vines to grow too closely to the base of trees.
In the accompanying photos you will see one of the best examples we have ever seen as to why these practices are detrimental and can cause the death of a tree or shrub.
When trees germinate from seed, the bark above ground develops a different outer skin than the roots below ground do. The bark covering the roots takes on a different consistency that allows them to handle a wetter, underground environment. The bark above ground, however, is meant to ‘dry out’ quickly after becoming wet.
The Hazards Of Piling Mulch On The Base Of Trees Or Allowing Plants To Grow Too Closely To The Base
In the above photos, you will see a white mold/fungus attached to the base of a Crab Apple tree. This was caused by allowing Boston Fern plants to spread and encroach too closely to the trunk. The Boston Ferns were already cut down to ground level in preparation for winter, but our customer confirmed that every year they grow to three feet tall, completely surrounding the trunk of the tree. What this does is trap moisture on the tree trunk every time it rains or when a sprinkler activates to water the garden. This begins the rotting process and in advanced stages, could eventually kill the tree by disrupting the carrying of water throughout the tree which flows just beneath the outer layer of now rotted bark.
This type of trunk damage occurs much more frequently when mulch is piled up and onto the trunk. It is OK for you or your landscaper to put 2 to 4 inches of mulch in your gardens but try to keep it at least 6 inches away from the base of your trees or shrubs. Putting more than 3 or 4 inches of mulch over the root zone can smother roots, depriving them of oxygen and preventing the lighter rains from penetrating the thick layer of mulch.
If you hire a company to mulch for you, we suggest that you tell your landscaper in advance to follow these guidelines.