The Complete Guide to Mulching Around a Tree Like a Pro

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How to mulch a tree for healthy roots

Co-authored by Savannah Vold Reviewed by Ben Barkan

Last Updated: August 3, 2024 Fact Checked

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Adding a Proper Mulch Bed

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Mulch Bed Maintnence

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Removing an Existing “Mulch Volcano”

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Video

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Things You'll Need

Putting mulch around a tree makes lawns more attractive, controls weeds, and helps maintain soil moisture. However, if you apply mulch incorrectly, you can stimulate fungus growth, attract insects, and starve the tree's roots of oxygen. Luckily, expertly mulching around a tree is easy as can be if you follow our simple and effective steps. Read on for magnificent mulching!

Things You Should Know

Shovel away old mulch, rocks, grass, and/or weeds from around your tree’s base to prepare your tree’s root flare for fresh mulch.
Spread an even layer of medium-textured mulch in a 4–5 ft (1.2–1.5 m) diameter around the tree, leaving 1–2 inches (2.5–5.1 cm) of space between the tree and the mulch.
Continue to spread an even layer of mulch around the tree until it’s 2–4 inches (5.1-10.2 cm) deep, adding stones around the mulch’s edge to create a barrier, if desired.

Method 1

Method 1 of 3:

Adding a Proper Mulch Bed

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1
Select a medium-textured mulch. Fine textured mulch gets compacted and will starve your tree's roots of oxygen, while coarse mulch is too porous to maintain adequate water levels. A medium-textured mulch will hold water and won't starve the tree's roots of oxygen making it the perfect choice for use around your tree.^{[1]
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- Organic mulches include wood chips, bark, pine needles, leaves, and compost mixes.
- If you're unsure how much mulch you'll need, type "mulch calculator" into a search engine to find online tools to help you calculate the amount.
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Spread mulch in a 4–5 ft (1.2–1.5 m) diameter around the tree. Apply a thin layer of mulch around the tree, not touching the tree itself. Leave 1–2 inches (2.5–5.1 cm) of space between the base of the tree and the mulch.^{[2]
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- Remove any existing mulch, if necessary, by shoveling or spading it away.
- Avoid creating a “mulch volcano” (pile of mulch around the tree’s base), as it will cut off your beautiful tree’s access to the oxygen it needs to thrive.
- Mulch stops serving a purpose after covering up to a 8 feet (2.4 m) diameter around the tree.
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Keep layering the mulch around the tree until it's at the proper depth of 2–4 inches (5.1–10.2 cm) and is spread level around the tree.^{[3]
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Pile about 1 inch (2.5 cm) of extra mulch around the edges of your mulch bed to create a barrier that will prevent your freshly laid mulch from washing away when it rains. Placing rocks around the mulch bed is another effective and stylish way to create a barrier as well.^{[4]
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Method 2

Method 2 of 3:

Mulch Bed Maintnence

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Pull or kill weeds that grow out of the mulch. Mulch acts as a barrier for weeds and grass. Pull any weeds or grass that begin to grow out of the mulch bed throughout the year to prevent future growth and disruption of your tree’s root system.^{[5]
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- Apply herbicide, (chemical weed killer) around your tree to prevent grass and weeds from growing in your beautiful new mulch.
- If you use an herbicide, ensure it's safe around trees.
Compacted mulch prevents oxygen from passing through, will starve your tree's roots, and often occurs due to excessive rainfall or people walking over it. Loosen compacted mulch by raking it.^{[6]
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Mulching around the tree once a year will prevent weeds, provide essential nutrients, and help with the tree's drainage. Healthy, happy trees, here we come!^{[7]
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Method 3

Method 3 of 3:

Removing an Existing “Mulch Volcano”

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Shovel away all the old mulch, debris, and rocks so that the tree trunk is visible. A "mulch volcano” occurs when mulch gets piled up year after year around the base of a tree. This is detrimental, as it starves the roots of necessary oxygen.^{[8]
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Remove girdling roots with a girdling chisel and mallet. If you notice any roots growing upward around the tree as you clear away old mulch, remove 1-2 inches (2.5–5.1 cm) of the root where it contacts the tree trunk. Position your girdling chisel at the desired cut point and use your mallet to pound the shear into the root.^{[9]
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- Removing girdling roots will ensure that these roots do not reconnect and cause problems later down the line.
- Girdling roots (roots visible around the tree's base) indicate that the tree is starved for oxygen and will wrap around the tree's base and kill it over time.
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Remove grass and other weeds around the tree with a spade. Scrape the area around the tree's base to remove weeds and/or grass. Once you shovel away the excess mulch, dirt, and rocks, you’ll see the primary root flare around the tree's base.^{[10]
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- Mulch will act as a natural weed barrier.
- Avoid using roll-out weed barriers, also known as landscaping fabric, as these will starve the tree of oxygen and compact the soil underneath them.^{[11]
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