How To Mulch A Tree: The Expert Guide

how to mulch a tree - mulch for tree

Understanding how to mulch a tree and shrub will help you guide your tree to optimal health for years to come. Mulching around your tree is one of the easiest, quickest, and most cost-effective things you can do to support it.

Here’s a quick rundown of why it’s important to know how to mulch a tree:

Benefits Of Mulching:

  • Enhances root growth which improves overall tree health
  • Nearly doubles the growth rate of newly planted trees
  • Can create a buffer between temperature changes
  • Helps retain root and soil moisture
  • Protects against root competition and soil compaction
  • Helps tree soil retain its essential nutrients
  • Reduces lawn mower damage

Consequences of Improper Mulching:

  • Increases susceptibility to insects & diseases caused by mulch irritation on the trunk of the tree.
  • Girdling Root Systems – a condition where smaller roots wrap around a dominate root. This chokes the tree, which makes it absorb essential nutrients it needs to survive.
  • Rodent issues – mulch piled high against the trunks of trees create habitats for rodents that chew the tree’s bark.
  • Root Rot from excess moisture

In our Northern VA, MD, and DC tree service area, we unfortunately see a lot of improper mulching practices. In this article, we’ll guide you through how to mulch a tree; this way, you can avoid making the top 5 mulching mistakes.

How To Properly Mulch A Tree

Q: When should you mulch around trees?

While mulch can be applied to your trees at any time of the year, the best time to mulch is in the spring season. Certified Arborists and tree service experts alike generally recommend that you mulch around trees in mid-spring, when the temperatures consistently stay warm.

Size: How wide should mulch be around trees?

Drip line used to help learn how to mulch a tree

The best mulching goes out as far as the tree’s canopy, referred to as the drip line of the tree.

Mulching this far out covers the tree’s “life veins” (“critical root zone”/CRZ). By doing this, you’ll be applying the mulch where it matters most (where the feeding and nourishing happens).

Most homeowners don’t like to apply mulch around trees in this way. They either don’t like how it looks, or they have big trees on small properties.

If mulching this far out isn’t practical, you can apply mulch in a 2 to 3-foot radius around the tree.

Depth: How Deep Should My Mulch Be?

You should apply mulch about 2-4 inches deep. Most mulching you see is likely a lot deeper than this, as over-mulching is one of the most common mulching mistakes.

It’s become a common practice to pack 6-12 inches of mulch up around the base of the tree; however, this over-mulching is very bad for your tree and can result in the many issues we discussed earlier.

Need Help With Soil & Root Care?

Expert Tips On How To Mulch A Tree

How to mulch a tree: make sure when you place mulch around a tree, that you can still see its root flare!
  1. Keep Mulch Away From The Tree Trunk
    • Do not pile the mulch against the trunk of the tree, as this can cause the roots to grow in a way that causes them to choke each other. Instead, keep the mulch away from the trunk, so that the root flare zone (shown on the right) is visible.
  2. Remove Last Year’s Mulch
    • If you want to refresh the mulch, don’t pile the new layers on top of the old. Instead, lightly rake the top layers of the mulch, or simply remove the old mulch and replace with new mulch.
  3. Don’t Use Fresh Wood Chips For Young Trees
    • Do not use fresh wood chips for mulching around young trees, as they can injure the tree.
  4. Yes, you can use pine needles as organic mulch.
    • If you have a healthy pine tree, then you can save money by opting for pine needles. They typically last longer and are more durable against harsh weather. With that said, it’s important to avoid using them if wildfires frequent your area, as pine needles are flammable and can easily ignite fire.
  5. Q: Can too much mulch kill a tree?
    • A: Yes! By adding too much mulch around a tree and committing the ever-too-common mistake of building a mulch volcano, it’ll actually be too much of a good thing. Too much mulch can lead to poor soil and root health, which will lead to tree decline.

How Do I Know If I’ve Been Mulching Correctly?

how to mulch a tree: check the root crown to see if it moves when you press down on the tree trunk!

As you can see, it’s important to understand how to mulch a tree. After all, 80% of tree health issues are connected back to the tree’s roots, so it’s vital for them to be in tip-top shape.

Quick Tree Care Tip From A Certified Arborist:

A quick and easy way to check how well your tree is doing is to push on the tree trunk and then look down at the tree’s root crown (pictured at the right).

If this area heaves up or if your tree seems to rock when you push down on it, then you’ll want to have your tree checked as it may have girdling roots.

*IMPORTANT: If GRS (girdling root syndrome) is not addressed and resolved immediately, your tree will experience chronic decline over time.

What Should I Do If I’ve Been Mulching Incorrectly?

how not to mulch a tree - avoid mulch volcanoes
When learning how to mulch a tree, remember to avoid making mulch volcanoes!

If you have just recently over-mulched your tree, you can simply go out and fix it. You can redistribute the mulch to best support your tree’s needs, as long as you follow the instructions above.

But, if you’ve accidentally been over-mulching your tree for years, or you have other concern for your tree’s soil and root health, you will want to turn to your Certified Arborist for help.

To improve your tree’s soil and root health, you can:

  • Have your Certified Arborist assess your tree’s roots: Through root collar excavation, your tree service expert will be able to open up and assess the tree’s root zone to see if it may be experiencing girdling roots or root rot.
  • Ask about our root care package: If your Certified Arborist discovers underlying root issues, don’t worry. We have a root care package that will help you supply your tree with the essential nutrients it needs and is likely missing from its urban environment.
  • Apply the best organic multivitamin: Our Certified Arborists like to say that if you can do one thing for your tree, it’s apply biostimulants. Biostimulants are an all-natural, organic solution that nourishes your tree, strengthens its immune system, and can help your tree and its root system recover from poor root and soil health.

If you need help with your soil and root care this spring, you can reserve an appointment with one of our Certified Arborists through our online booking system or by calling us at 703.573.3029.

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