Learn how to mulch around trees in 5 easy steps.
Follow this step-by-step guide to discover why and how to mulch around trees.
There is a lot of misinformation floating around about how to mulch around trees.
Even some professional landscape contractors do it incorrectly, not realizing that too much mulch can damage a tree irreparably.
The best way to mulch your trees is to understand the horticultural purpose of mulching in the first place, so you can create the healthiest environment for your trees.
In this post, you will learn how to mulch trees in 5 easy steps:
- Determine the size of the mulch circle you wish to establish around your tree.
- Remove weeds and turf (lawn grass) before putting down mulch.
- Decide which type of mulch you want to use.
- Add 2-3 inches of mulch around your tree.
- Maintain your mulched trees correctly.
Note: If you have any questions about how to care for a specific tree in your landscape, do not hesitate to contact a local certified arborist. Or reach out to your local cooperative extension office for detailed advice.
How to Mulch around Trees: The Main Steps
Here are the steps to follow:
1. Determine the size of the mulch circle you wish to establish around your tree.
Mulching trees makes the landscape appear well-tended. Yet, there are other important reasons to do it.
Mulching around trees prevents damage to bark.
Mulching prevents the need for lawnmowers and weed-whackers to get near trees. Why is this important? Because these tools can nick the tree bark or exposed roots and cause wounds.
Obviously, this is not a good situation. Yet many folks do not realize this is a problem.
According to Bartlett Tree Experts, bark wounds can damage the vascular tissue of the tree and open it up to decay and infections. This can be deadly.
Ideally, a mulch circle should extend out to the edge of the tree’s canopy or drip line, the entire area under which the tree’s branches extend.
Even a smaller circle is helpful to keep lawn turf and weeds from growing around the base of the tree.
In general, a mulch circle extending in a 3′ radius from the base of tree trunk is a good place to start.
2. Remove weeds and turf (lawn grass) before putting down mulch.
Mulching eliminates competition from your lawn.
A tree’s feeder roots usually reside in the top 12″ of soil and extend far beyond the tree’s canopy.
These roots that absorb water and nutrients the tree needs to sustain life. However, when turf grass (aka your lawn) grows in this area, it also absorbs water and nutrients, especially nitrogen.
If you can imagine a tree growing in a natural woodland setting, there would usually be decaying leaves or plants under the tree, not lawn. Mulching under trees in the landscape provides a setting similar to nature.
Thus, allowing a tree’s fallen leaves to remain on the ground in the fall and winter allows them to break down so the tree can recycle them as nutrients.
The removal process can happen in any number of ways. It is truly worth a phone call to a certified arborist, reputable nursery, or extension office to advise you. Every tree and every landscape are different. Do not trust random advice on the internet about this!
Removing grass and weeds around the base of a tree should be done with great care, so as not to damage the tree’s feeder roots.
3. Decide which type of mulch you want to use.
Personally, I think undyed shredded bark mulch looks the most natural under trees. I use a neutral-tone cedar mulch because it is so light and easy to handle.
Red and black dyed bark mulches can appear unnatural in the landscape, but some folks enjoy the contrast of color.
Alternatively, stone or rubber mulches are not a good idea to place around trees, even if they look nice. They do not break down to add organic matter in the soil. These types of mulches are a huge hassle to maintain over time, especially when weeds begin to grow in them.
Be aware of the artillery fungus (Sphaerobulus stellatus), which can live in mulch. It can do serious damage to your home’s siding or paint. Even your car can sustain damage from the tiny black spores launched by this strange organism, sometimes up to 20′ feet away!
You can try to avoid this fungus by getting your mulch from reputable sources. Make sure there is good air circulation around the mulch, and that it is not piled too deeply.
Mulch is sold in cubic yards. To determine how much you need to buy, you can do the math. Or make it easy with a mulch calculator that lets you choose the shape of your mulched area.
4. Add 2-3″ of mulch around your tree
Add no more than 3” of mulch after you remove weeds and turf, but not more. I use my hands to spread mulch and find it much faster and more precise than using a shovel or pitchfork.
Quite simply, too much mulch can cause the tree to suffer a slow death.
The most important thing is not to let any mulch touch the tree itself. And absolutely do not mound the mulch around the base of the tree, which you might see done in your neighborhood.
When you see a pile of mulch mounted up against the base of a tree, it’s often called a “mulch volcano.” Do not do this!
Just say no to mulch volcanoes
A mulch volcanoes create the following problems:
- Shelters pests like voles, who chew on the tree roots.
- Harbosr pathogens.
- Causes rot.
- Provides a medium for adventitious roots (roots that develop above ground), which can dry out during hot spells, and damage the tree.
- Encourages root girdling (adventitious roots encircle the tree and eventually cut off its vascular system).
- Acts almost like a compost pile and heat up the base of the tree, causing tissue decay.
- Forms a hard crust that prevents oxygen, water, and nutrients from being available to the tree’s roots.
The flare of the tree (the place where the roots begin to flare out from the tree’s trunk and go underground) roots should always remain visible and free of mulch.
Professional contractors often create mulch volcanoes because their customers like them. Or perhaps they do not want to take the time to remove last year’s mulch, so it continues to build up.
Many people mistakenly imagine a mound of mulch to be a good thing, as a way to protect the tree.
Take a walk in the woods and observe how trees grow in nature and take your cues from that.
Note: Do not use landscape fabric under your tree mulch. Although it allows water to pass through to tree roots, it creates two main problems:
- Mulch breaks down on top of the fabric and provides a medium in which weeds can grow. The weeds usually getting entangled with the fabric and creating headaches down the road.
- Landscape fabric does not allow the mulch that breaks down to enrich the soil beneath it.
Here is an excellent video from This Old House demonstrating the results of improper mulching (and how to fix it).
5. Maintain your mulched trees correctly.
After you mulch around your trees, you will need to continue to remove any weeds and turf that pop up during the growing season.
Ideally, leave any fallen leaves in the mulch over the winter, Then, they can break down and add nutrients to the soil for the tree to absorb and use.
If you can’t leave dead leaves in place in the fall, lightly rake them from the base of the tree, trying not to disturb the mulch.
You can shred fall leaves with a leaf shredder and add them back under the tree, lightly raking them into the existing mulch up to a depth of 3″ total.
In the spring, lightly rake your tree mulch to remove debris. If needed, add a layer of new mulch on top. If you prefer to start over with all new mulch every year, be sure to remove the old mulch so as not to exceed the recommended 3″ depth for tree mulch.
Tree Mulching FAQs
What time of year is best to mulch around trees?
You can mulch around a tree any time of year as long as you are able to remove weeds and turf first. However, you should not work around a tree or in garden beds when the soil is wet. This can cause you to compact the soil, which damages fine tree roots and causes long-term negative effects for the soil.
How do you edge the mulch around trees?
You can use an edging tool to create a clean border between the mulch and your lawn. Be careful not to damage any tree roots when doing this. Do not add a raised border of edging material, bricks, pavers, stones, or wood. This can change the grade of the area around the tree, because this can cause too much mulch piled around the tree (see mulch volcanoes above).
What is the best way to buy mulch?
Bagged mulch from a big-box store is fine. Just make sure it isn’t sopping wet from being stored in the open air, which makes it hard to transport and carry. Nurseries and garden centers usually have bulk mulch available for pick-up or delivery. Ask a reputable local nursery or landscape contractor for recommendations.
Can I use wood chips around trees instead of mulch?
Wood chips (as opposed to shredded bark) initially deplete nitrogen and are too chunky to work well as mulch around trees. That said, many municipalities offer free woods chips to residents. These can be used to make excellent walking paths through woodland areas.
What are alternatives to mulching around trees?
You can remove turf grass and plant groundcover or understory plants instead, which is generally how trees grow in the forest. See my post on groundcover plants for ideas on what to plant under a tree.
Check out The Cornell Guide for Planting and Maintaining Trees and Shrubs for a comprehensive guide to caring for trees in your landscape.
Post updated 4/26/2023
