Mulching The Right Way
Mulching trees and landscape beds the right way is a rare sight these days. Whether done by professional companies or done by "do it your selfers", the "more is better" doctrine seems to rule. There seems to be little regard for how much material is already there. Just throw another four inches on because....well it just seems like the right thing to do? Well it's not. Yes, too much of a good thing can be detrimental to plant health.
The most common and potentially serious mistake, is the excessive amount of material applied year after year to the base of trees. When too much is applied to the base of tree, "mulch vocanoes" are formed. These mounds hold moisture against the base of the trunk which can lead to bark decay. They also create the perfect environment for girdling roots to form. Girdling roots can grow around the the trunk or major butress roots severely stressing the tree.
The most popular materials are the organics. When properly applied, organic materials can be a huge benefit to your landscape plantings. Organics break down over time, releasing nutrients into the soil. Besides inhibiting weed germination and growth, they help to retain moisture and keep soil temperatures down. Among the organics are materials like shredded hardwood, cedar and cypress. Pine bark, pine straw and cocoa shells are also popular. Many people have also found the value in using shredded leaves. This is great way to get rid of leaves in the Fall.
On the other hand, inorganic material like rocks or rubber are popular in low maintenance situations. Caution must be used however. These materials don't break down and keep soil temperature elevated.