Updated: Mar 24, 2022
So with the arrival of each spring, one of the first things that most homeowners look to do right away is mulching their beds. Seems like a simple enough task but there are so many people, including contractors, who still mulch incorrectly.
You're probably saying to yourself, "Mulching incorrectly?" Yes. There are some simple but important procedures for mulching that will ensure you don't unintentionally harm your plants and trees.
Many times we visit homes and we find piles and piles of much around trees and shrubs even practically burying perennials. There is definitely such a thing as too much mulch. This is much more of a problem because people will think they have to cover every inch of ground with mulch because it will retain water for their plants. While this is a common perception, mulch doesn't actually retain a tremendous amount of moisture but rather the wet mulch will tend to keep the roots around plants cooler in the heat and warmer in the winter thus lessening their susceptibility to temperature stress.
While we want enough mulch to block out sunlight which suppresses weed growth, piling mulch up around the root flares of trees and shrubs can lead to health problems for the plants. As mulch breaks down, composts it creating a matted, attractive substrate for roots to grow in and trees will send shoots out from their trunk to seek a more advantageous depth for the air-water exchange they need to prevent suffocation. These extra roots often will lead to girdling of the trunk. This means that the roots will wrap themselves around the base of the tree strangulating the tree's vascular system, weakening and shortening the tree's lifespan.
Mulch that is placed too high also creates an environment in which insects can use to infiltrate a tree because the base of the tree never gets an opportunity to fully dry out leading to continuous dampness creating rot or splits in the tree structure. Many insects love soft, damp wood as it is easier to bore through.
Leave your mulch a few inches away from the base of the trees to minimize the potential of unwanted root shoots robbing the plant of its natural growth. For trees we recommend that you follow the ISA standards and keep mulch at least 6" away from the root flare allowing for bare earth to be visible around the tree. I know some of you out there will say "now I will have weeds growing in there!" I can't say that you won't but a few weeds that need pulling is a lot better than a dead tree in your yard.