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Can Mulching Actually Damage My Plants?

31 Dec , 2015  

As a matter of fact, mulching is one of the best things that can ever happen to your plants. However, incorrectly applied or too much mulching can cause a lot of problems. How so, you might ask. The common practice of mounding too much mulch against the plant’s base has proven a fatal one for a wide variety of plants. What has made the problem worse is that many of the plants on commercial properties have heaps of mulching piled against their bases, often a perfect circle of 8 to 10 inches thick. Since these plants are under professional care, this has helped to create the false impression that it is the proper way to mulch plants in our yards.

The neat, clean appearance it gives their landscape is appealing to a lot of people. As such, you will find a lot of garden owners asking if there is a mold they can purchase to easily make the mulching heaps on their own. What they don’t realize is that in their quest for a gorgeous landscape, they are unknowingly sacrificing the health of the plants in their gardens in the long run.

Why does it harm plants?

To start with, the bark on the roots of a plant is quite different from the bark on its branches. For one, it is able to tolerate moisture in addition to lower levels in the soil. On the other hand, the above-ground portion of your plants, which starts at the root flares, have barks that contain millions of small openings which are utilized to release toxins and gases from their systems. On plants such as forsythia (cherry trees), these tiny spots are easily seen as small white dashes or dots on the bark, and which are commonly referred to as root flares. By piling heaps of mulch against them, you are simply preventing natural respiration from the bark, causing a buildup of toxins and gases in the bark tissue.

What’s the issue here?

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If heaps of mulch or soil disrupts the natural respiration of the bark, the plant eventually responds in one way or another. On thin-barked young plants, or plant species with naturally thin bark, such as linden, beech, and the likes, this disruption causes a lot of wounds or cankers on the trunk. Cankers appear as spots of dead tissue that then offer a chance for decay to enter the plant. Some plants respond by sending out extra roots from the trunk.

The additional roots will end up encircling the trunk and becoming girding roots in the future. Studies have proved that plants such as trees with girdling roots and excessive mulch and soil build-up are more prone to snapping off at the base in wind and snow storms. The longer the problem has existed, the more damage will occur.

Chances of correcting this kind of an issue at this stage are significantly reduced. However, it should be noted that all plants will not respond the same way when excess mulching is applied. As such, the plant’s health, age and species all need to be considered when trying to examine the effects of the past damage. Plants such as the willow tree are quite adaptable to the change of grade and hence are unlikely to show any issues at all.

Can the issue of excess mulching be fixed?

If caught soon enough, the problems associated with excess mulching are easy to reverse. Nevertheless, if it is found that huge cankers have already formed, and decay is present, or the plant has developed too much girdling roots, the best way forward is to completely remove and replace the plant than to attempt to save it.

Proper mulching

While it is quite common to see 4-6 inches of mulch around plants, this is normally too much. The recommended level is 2-3 inches properly placed in a ring around the plant with the center around the trunk empty. How wide the ring is made is up to the gardener, but the farther the better. All in all, properly mulched plants in Brooklyn often have fewer issues than any others around them.