Posted: March 13, 2024

Nothing livens up your home landscape beds like a fresh layer of mulch.

And aesthetics aren’t mulch’s only benefits, especially when mulching trees. You’ll be surprised at how many things mulch does for your favorite woody giants.

You might think mulching requires no skill – just apply it and you’re good. But there is an art and science to mulching correctly so that you reap all the benefits.

Let’s review why you should mulch around trees, the proper way to mulch around trees, and answer the question, “Can too much mulch kill trees?”

Why You Should Mulch Around Trees

Is it good to put mulch around trees? According to Kansas State University research, it’s actually the best thing you can do after you plant a tree.

Mulch helps your soil retain moisture, suppresses weed growth, acts as a great insulator to keep temperatures more consistent, can increase soil fertility, and even helps prevent soil compaction and increase aeration by breaking down and adding organic matter to the soil. All of these perks can increase root health, improve your soil’s physical structure, and reduce any lawn mower and string trimmer damage to your trees by putting some space between the lawn and your tree.

Need more reasons to embrace tree mulch in Massachusetts? Check out these facts.

1. Mulch Reduces Weeds

You probably love your trees, but you may not like it when weeds grow up around them. Weeds are not a big favorite on anyone’s plant lists.

By just properly mulching around your trees, you can reduce weeds by 45% to 85% the second year after it’s applied. That’s fewer weeds you have to pull from your yard.

How does this work? Mulch actually limits the light the weed seeds receive, reducing their chances of germination. If you want to maximize this perk, opt for thick, coarse, organic mulch over finer options.

2. Mulch Adds Nutrients

Is mulch good for trees? In fact, the appropriate amount of mulch – 2 to 3 inches – adds nutrients and organic matter to your soil, improving the environment for your trees.

3. Mulch Insulates Roots

Mulching trees helps insulate their roots, keeping them at a more even temperature, despite the more extreme fluctuations in the air above.

This is a healthier environment for your tree roots to thrive in.

This means your tree can take in the nitrogen, phosphorus, and potassium it needs from the soil as it needs it because your soil is more nourishing.

4. Mulch Helps Keep the Soil Moist

Trees need water; we all know that. But by mulching your trees, you can reduce how often you need to water because that mulch helps reduce water evaporation by 35% when compared to bare soil.

What’s more, with mulch you also reduce any soil erosion that can take place up to 86% because it helps keep that soil in its place.

5. Mulch Can Help Increase Tree Growth

Mulching trees has been shown to nearly double a tree’s growth rate compared to trees that just grow in grassy areas.

In fact, fine hardwood trees like oak, maple, hickory, beech, birch, and cherry can grow 79% more with the addition of mulch

Can Too Much Mulch Be Harmful?

As you can see, mulching trees offers a ton of benefits. But, as with anything, it needs to be done correctly. There can be too much of a good thing.

Piling the mulch too high around a tree’s trunk, for instance – a process known as “volcano mulching” – can cause some issues for the tree.

First, excess mulch can smother a tree’s roots, causing them to grow up in search of air and wrap around the trunk or “girdle” it, cutting off its water supply.

Too much mulch can also cause moisture to build up on the tree trunk, encouraging wood decay and fungi, which can deteriorate tree bark and lead to an unstable foundation.

Proper mulching involves applying a 2- to 4-inch even layer out about 3 to 6 feet around the tree. And mulch shouldn't touch the actual tree trunk. Think of it like a donut with that hole in the center. Ideally, you want to replenish mulch yearly as it breaks down.

But like any organic material, shredded hardwood bark mulch has a shelf life in your landscape. Overtime, rain, erosion, and decomposition will deplete the mulch. That means replenishing your mulch on a regular basis is vital to maintaining these benefits and keeping your trees healthy. Ideally, you want to replenish mulch yearly as it breaks down.

At Hartney Greymont, we have both ISA and Massachusetts certified arborists located in Needham, Concord, Danvers, Cape Cod, and the surrounding areas to help educate you on proper tree mulching and tree care.

Contact Hartney’s ISA And Massachusetts Certified Arborist For Tree Mulching Tips.

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