Tree Care Services of Vancouver, WA and Portland, OR

Why Mulch May Hurt Your Trees

By AK Timber in Tree Care

“Put mulch around your trees,” is one of the biggest pieces of advice you’ll hear when you tell someone that your trees aren’t looking healthy. “It is one of the best things you can do for it,” they’ll tell you, along with some long-winded story about how their trees are beautiful now. Mulch is truly a great product – it can make all the difference in your gardens. Why is it a great addition to many gardens? It minimizes the amount of weeds in the soil around the tree, assists with moisture retention in the drier months, keeps soil temperature level, and also it looks better than the simple ground does at many homes.

Still, there are some problems with mulch that people don’t tell you about.

You have to be careful when it comes to placing mulch in your yard. It isn’t something that you can do haphazardly or quickly – you may be doing more damage than you are doing good.

Here are a few things to take into consideration when you apply mulch around your tree:

Root Girdling

  • Leads to excessive dieback of tree
  • Girdling stunts the growth of trees
  • Makes tree at risk to various other diseases

When a tree is girdled, there is a band that goes around the bottom of the trunk. Mulch can sometimes cause girdling, especially if you use those rubber mulch mats that are basically made out of tires. Girdling threatens the livelihood of the tree because it causes a blockade on the flow of nutrients and water to the rest of the tree. Over time, your tree will certainly start to wither away.

Your tree will begin to look really, really different when it has a root that is girdling the bottom of it – note that girdling can appear around branches as well. Normally, when it is around the root, the tree’s trunk will begin to flare out near the surface of the ground. Sometimes you won’t see this at all. Instead, you will see the tree getting narrower, according to the Missouri Botanical Garden. They say that,The threat depends on the size of the root and the amount of the tree’s circumference affected. It is almost impossible to predict if a developing girdling root will cause problems for a tree. However, if a tree has girdling roots it is more likely to have problems than one without them.”

You Might Cut Off the Oxygen Supply

  • Roots need oxygen to help the tree grow
  • Tree development can be cut off at any stage
  • Eventually, suffocation could occur

All plants, including trees, need oxygen to make it through their growth and regeneration. This is because without access to clean oxygen, the trees cannot carry out something called aerobic respiration nor can they complete photosynthesis. This process utilizes water, co2, and the sunlight’s power to produce oxygen. This happens around the tree, however not in the origins, according to USCB Science Line.

The tree is able to get air from the dirt near the roots to carry out photosynthesis — yet with too much mulch too close to the bottom, it is most likely that the dirt is compacted and doesn’t have as much air.

Mulch Can Push Soil to the Trunk

  • Traps water in and creates a greenhouse under the mulch
  • Triggers tree bark to decay and softening
  • Trees are extra susceptible to fungus

One of the biggest reasons people decide to put mulch around their trees is to get a more consistent, beautiful look. But you have to think about the heat and water that the mulch creates around the roots of your tree.  As the ground heats up, your tree’s trunk and roots will soften and that can cause many different problems.

Soil isn’t always great for your trees – especially when it is packed around the base. SFGate explains why: “Soil added around a tree reduces the amount of oxygen available to the roots and slows the rate of gas exchange in and around the roots. There may be less moisture and nutrients available to the roots or too much moisture may remain around the tree’s roots. Inadequate oxygen reaching the roots or microorganisms in the soil around the roots can lead to an accumulation of chemicals that can injure tree roots. The tree’s bark may decay where soil is newly in contact with it. Damage or injury to the tree because of the added soil may not become apparent for several months or years and generally appears as a slow decline followed by death.”

There are many other options besides mulch to help your tree feel and look attractive. You have to be judicious what you do with mulch. Most importantly, you want to find a mulch that is high quality and uses only natural products – or it can leech into the ground and cause even worse problems.

Note that some of these issues can occur with natural mulch and rubber mulch as well, though they seem to be exasperated with rubber mulch. You need to beware when you spread mulch and you should constantly check your tree for any type of troubles that you see.

No matter what type of trees, shrubs, or plant life you have, you want to keep them protected and cared for as much as possible. Your soil can only do so much to keep the water going to the roots, your tree can only do so much work on its own, and then you will need some help to back you up. Contact AK Timber Services for all of your tree care needs – we can help you at any stage of the tree process, from planting and taking care of your tree to pruning and cutting it down to watering. Call us today at (360) 635-1076 for all of your tree care needs – we offer free estimates.

Header photo courtesy of Phil Roeder on Flickr!