The Dangers of Over-Mulching

There are tons of advantages of using mulch in your garden and as part of your landscaping. For example, it can help keep your plants moist and protected, plus it looks great! However, there is such a thing as too much mulch. In fact, an excess of mulch can actually cause serious problems for plants and trees. In order to avoid these risks, let’s take a look at some of the problems that can come from over-mulching.


1. You could suffocate your plants.

Plants need oxygen to thrive and they get the oxygen they need from their roots. When you cover them up with too much mulch, you can trap too much water in, reducing access to fresh air and ultimately causing oxygen starvation. While this is actually one of the most common reasons plants die. This is typically a bigger problem in spring and fall, or in areas where rainfall is more substantial. Symptoms of oxygen starvation in plants generally include yellowing leaves, small leaves, and poor twig/stem growth. Unfortunately, by the time you see the symptoms, it’s usually too late to save the plant.


2. You can trap too much moisture and cause root rot.

This problem can go hand in hand with a lack of oxygen since it’s created by an excess of mulch trapping too much water in the soil around your plants and trees. A perfect example of this is when landscapers use volcano mulching. While some think this style of landscaping is attractive, it’s also deadly. The incredible amount of mulch used in volcano mulching causes the soil to become waterlogged, providing the perfect environment for disease and root rot to thrive. This excess of water can cause tree roots, cambium, and bark to break down and can cause smaller plants to succumb to the effects of root rot in no time.


3. You can cause plants to overheat.

Mulch is basically always decomposing very slowly, and releasing heat is a normal part of the decomposition process. It’s somewhat similar to composting and can cause the temperature underneath your mulch to reach up to 140 degrees Fahrenheit. It probably goes without saying that this extreme heat will certainly kill trees and plants, but it can also prevent the hardening period that many plants go through in the fall to prepare for the winter. If stems and trunks do not harden appropriately, they will likely starve or succumb to colder weather come winter.


4. Fungal and bacterial growth is encouraged.

Since over-mulching tends to create a warm, moist environment, it’s no wonder that it also creates the perfect atmosphere for bacteria and fungi to grow. This kind of environment also encourages the growth of canker diseases. Any of these organisms, once established, can decay bark tissue, rob the plant of nutrients, and kill it.


5. You’re giving rodents and pests the perfect place to live.

Small rodents, like mice and voles, along with pests like beetles and other boaring bugs, look for places to live that are well shaded and out of sight of predators. For small animals like this, few things look more attractive than a nice warm, camouflaged, pile of mulch. Pests like these love to feed on the tasty flesh of trees and plants, which can easily kill them. Unfortunately, gardeners don’t usually realize this is happening until spring comes and they realize their plant doesn’t look so good, at which point it’s usually too late.

Fortunately, avoiding all of these issues is pretty easy - just don’t use too much mulch! A good rule of thumb is to use no more than two to three inches of mulch on any plant. Keep your mulch level, not in big piles, and make sure to leave a little space around trunks and stems for your plants to breathe. You can also help keep your plants healthy by investing in the high-quality organic mulch and screened topsoil available at American Property Experts’ two Wilmington locations. Drop by and visit us at 606 Sunnyvale Drive or 2831 N. Kerr Avenue in Wilmington, North Carolina, or get in touch with us if you have any questions!

© 2021 American Property Experts. All rights reserved.
Website Development & Hosting by BlueTone Media


Topsoil & Mulch Calculator

Please enter the dimensions of the space you need to cover with mulch or topsoil.

Our optimal height recommendation for mulch beds is 3 inches.



We have a $25 minimum

*Tax not included