Hey tree enthusiasts!

One of the more commonly asked questions we get asked here at Croft Tree Experts in Ottawa is in regard to mulch.

Should you put mulch in your yard? Is it beneficial? What should one avoid when mulching? 

To Mulch or Not to Mulch

In a nutshell (which can be used as a mulch, haha!), mulching is good. Why? Mulch brings a number of benefits to your lawn and garden.

  • Mulch keeps moisture in the soil
  • Organic mulches break down and contribute to soil health
  • It helps with weed control
  • Mulch also prevents injury in winter, from erosion and from lawn mowers, etc.
  • Some wood mulch can repel fleas, ticks and other unwanted insects

Great, you say, mulch away, right?

Yes, please do. But with a caveat (not a caviar, which is a poor mulch but an interesting albeit expensive fertilizer).

Use Caution with Mulch Around Trees (and Foundations)

As beneficial as mulch can be, there are certain areas you’ll want to avoid when mulching.

First up is – you guessed it (we’re the Tree Experts after all) – trees!

Mulch is not always a friend of trees.

Oh sure, it can provide nutrients and protection. Mulch conserves moisture, helps boost the soil and reduces weeds in the vicinity.

But mulch is kind of like fire. Not like fire for trees, but fire for humans – we need it to survive, but it can also kill us.

And to be clear, mulching the wrong way can kill trees.

Too much mulch suffocates a tree’s roots. It ends up choking the tree by cutting off its water supply.

Moisture can also build up to unhealthy levels, which could lead to issues such as wood decay, fungi, deteriorating bark and an unstable foundation.

So how do we know when mulch is good or bad? What’s the right way to mulch?


How Mulch Can Damage Trees

Mulch should not be placed next to tree trunks for the health of the trees. Despite the fact that mulch has several advantages, like soil insulation, weed control, and moisture retention, placing it up against a tree’s base can lead to a number of issues.

Moisture and Rot

The tree trunk may decay if there is an excessive amount of moisture retention. Bark deterioration may result from mulch that is in close proximity to the bark because it retains moisture in the region and encourages the growth of fungi. The entire health and structural integrity of the tree may be jeopardized as a result.

Pests and Disease

If mulch is stacked up against the trunk, illnesses and bugs may find a welcoming home. The damp, decaying organic debris provides a great home for some fungi, rodents, and insects. By gnawing on the bark or spreading illness, they can harm the tree.

Root Girdling

Cramping the base of the tree with a lot of mulch may induce roots to extend upward into the mulch in an attempt to get oxygen. This might cause “stem girdling roots,” a condition in which roots begin to wrap around the trunk of the tree, potentially obstructing the passage of water and nutrients.


Proper Mulch Application

In order to mulch trees correctly:

Create a Mulch Donut: Make sure to keep the mulch a few inches away from the tree trunk, creating a ring or shallow depression. As a result, water can enter without coming into close touch with the bark.

Proper Depth: Spread a layer of mulch that is uniformly thick, about 2 to 4 inches deep.

Extend Outwards: Spread the mulch layer as widely as you can to cover the majority of the tree’s roots, which are under the canopy.

You can preserve the integrity and health of the trees in your landscape while still enjoying the advantages of mulch by using these techniques.


Avoid Placing Mulch Too High Up the Tree Trunk

This practice is called “Volcano Mulching.” It looks like a volcano (see photo above) that has a crest or a peak at the tree trunk. And, much like an actual volcano, volcano mulching can be deadly.

Instead, what you’ll want to do is spread the mulch in a wider radius around the tree BUT make sure that it is spread more thinly – and be sure that the mulch is at its thinnest level right at the trunk. (see image at left)

In other words, the way to mulch is not a volcano but rather a concave mound.

Another place to avoid around your property is the foundation of the house or building.

Mulch near the foundation can draw termites as well as fungi. It also gathers moisture, which is the opposite of what you want around a foundation.

6-12 inches should be a good buffer, a mulch-free zone if you will.

Instead of mulch, use rocks, stones, bricks or other sturdy materials. That will help keep moisture away from the foundation, rather than drawing it nearer.



Croft Tree Experts Can Help with a Sick, Over-Mulched Tree in Ottawa

If you have trees that are the victim of over-mulching or mulching gone wrong, and look like they need to be cut down, get in touch with us today. We can come out to take a look at the trees and determine whether it can be saved. Click here to learn more about our tree mulching services!