Can you put too much mulch around a tree?

Applying too much mulch to the root ball or resting against the trunk (see the photos on the right) can cause problems for trees, especially when there are a wide variety of particle sizes. Roots often grow up and into the mulch, causing roots to curl up and can kill trees (bottom photo).

Can you put too much mulch around a tree?

Applying too much mulch to the root ball or resting against the trunk (see the photos on the right) can cause problems for trees, especially when there are a wide variety of particle sizes. Roots often grow up and into the mulch, causing roots to curl up and can kill trees (bottom photo). Root asphyxiation is the most common cause of death of trees and shrubs due to excessive padding. Repeated applications of mulch in areas with high rainfall or high levels of irrigation may contribute to waterlogging conditions.

Since water occupies most of the porous space in the mulch and in the upper soil layers, the air content is minimal and both the movement and the availability of oxygen are considerably reduced. Roots need oxygen to breathe, and when their soil level falls below 10%, root growth in most trees decreases. Once too many roots decay and die, the plant also goes into decline. As mentioned, applying too much mulch can be very problematic for the overall health of trees.

We recommend that mulch be stacked no more than 3 or 4 inches off the ground. It's also imperative that the mulch be kept away from the base of the tree, creating the appearance of a donut hole around the tree with the surrounding mulch. We recommend keeping mulch approximately 12 to 18 inches away from the trunk of any tree. Ideally, the mulch around the tree would spread along the branches or over an area of at least 4-5 feet in diameter around the tree trunk.

The larger the area covered with mulch, the more beneficial it will be. Too much mulch stifles a tree's roots. It ends up drowning the tree, cutting off its water supply. One of the most common causes of stress from excessive padding is asphyxiation of plant roots.

Repeated applications of mulch can contribute to waterlogging the soil and the root area by delaying the loss of water from the soil through evaporation. Roots must breathe (breathe) and absorb oxygen, unlike leaves, which give off oxygen. When oxygen levels in the soil fall below 10 percent, root growth slows. When too many roots decay and die, the plant will eventually succumb.

In general, the depth of the mulch should not exceed a total of 3 inches, including the remaining mulch from previous years and the current season's application. The mulch will dry out more quickly than the soil and much of the root system that has spread all over the mulch will die, affecting the overall health and survival of the trees. With thicker textured mulches, you can go a little deeper because of the better diffusion of oxygen through the mulch and “into the soil”. A slight raking of existing mulch may be all that is needed to refresh old mulch and break up compacted or crusty layers that may develop.

To neutralize the allelochems found in these toxic species, compost mulch with nitrogen at the rate of two pounds of real nitrogen per cubic yard of mulch. Allelopathic mulches are mulches that contain toxic elements that will inhibit the growth of other plants. Instead, what you'll want to do is spread the mulch over a wider radius around the tree, BUT make sure it's spread thinner and make sure the mulch is at its thinnest level, right in the trunk. A thinner layer of mulch over a larger area is much better than a mulch volcano for the health and longevity of the tree.

The best way to determine if you have a problem with excess mulch buildup in your garden is to go outside and simply dig through the layer of mulch to see how thick it really is. If you have smaller trees or trees that have only had volcanic mulch for a few years, you can probably dig up the mulch yourself with some garden tools. All that is needed is a slight raking of existing mulch to break up any compacted or crusty layer of mulch that can repel water and give it that finished landscape look. Volcanic mulching, also known as over-padding, is the improper mulching technique that stacks mulch around the tree against the tree trunk.

Mulching mimics the natural environment found in forests, where leaves and branches cover the soil surface, replenishing nutrients as they decompose and creating an ideal environment for root growth. . .To know more about tree mulching ask advice to a Tree Lopping Service.

Cairns Tree Lopping Pros
9 Cattleya Cl, Edmonton QLD 4869
(07) 4082 7223