Tree Talk

Too "Mulch" of a Good Thing

Written by Admin | 28/07/25 5:04 PM
Mulching is one of the simplest and most effective ways to care for your trees. When done correctly, it helps retain soil moisture, suppress weeds, and improve overall soil health. 

 

Can you have too "mulch" of a good thing?

Yes. Too much mulch—or improper application—can cause serious issues like root rot, insect infestations, and poor hydration.

In this article, we’ll share expert mulching tips and best practices to ensure your trees thrive. Whether you’re prepping for winter or enhancing your garden year-round, these guidelines will help you avoid common mulching mistakes.

Not all mulch is created equal. Mulch includes any material used to cover soil, while wood chips are coarser and often made from freshly chipped trees. Wood chips work well for established trees but may not suit young plants or gardens needing finer textures.

Avoid dyed mulches from garden supply stores. These often contain recycled wood from pallets or treated lumber, which can introduce harmful chemicals. The dyes can also leach into the soil, affecting plant health. Opt for organic, untreated mulch or composted wood chips for safer, more effective results.

 

 

WHY MULCHING MATTERS FOR TREE HEALTH

Mulch provides numerous benefits for trees and shrubs

 

 

 


(Above) Proper mulching technique:

The mulch covers the root zone in a donut shape. Mulch is not piled too high. The tree's root flare is visible and mulch is pulled away from the base of the trunk, exposing the root flare.

 
 

Step-by-Step Guide to Proper Mulching

 

  1. Check Soil Moisture and Nearby Plants Before Mulching

    Before adding mulch, inspect the area around your trees and plants.

    • Ensure the soil has adequate drainage to prevent waterlogging.
    • Check for nearby plants that might be affected by the mulching process.
  2. Check Mulch Depth

    If there’s already mulch in place, measure its depth. Mulch should be no more than 2–4 inches thick.

    • Rake old mulch to break up compacted layers and refresh its appearance.
    • Remove any excess mulch to avoid smothering the soil.
  3. Avoid Mulch Volcanoes

    One of the most common mistakes is piling mulch too high around the tree trunk—commonly known as a “mulch volcano.” This can:

    • Trap moisture against the bark, leading to rot and disease.
    • Restrict proper soil aeration, harming the tree’s root system.

    Best Practice: Keep mulch several inches away from the tree’s trunk and root crown. Mulch should be spread evenly in a donut shape, extending to the tree’s drip line or beyond.

  4. Choose the Right Mulch

    Organic mulches are ideal because they enhance soil health as they break down. Options include:

    • Composted Wood Chips or Leaf Mold: a composted mix that includes leaves, bark, and wood is highly effective and enhances soil quality
    • Fresh Wood Chips: Suitable for established trees and shrubs.
    • Other Organic and Green Mulches: Arborist mulch containing shredded leaves, branches, bark and twigs or other mulch mixes with pine needles or straw are unconventional looking but work as an organic fertilizer by infusing nitrogen back into the soil to enhance growth.

Avoid using inorganic materials like rocks or rubber mulch, as they do not provide the same soil-enhancing benefits.

 

Mulching Mistakes to Avoid:

  • Over-Mulching: Using more than 4 inches of mulch can suffocate roots and lead to poor aeration.
  • Improper Placement: Mulch that touches the tree trunk can create a breeding ground for pests and fungi.
  • Ignoring Existing Layers: Failing to rake or remove old mulch can result in compaction and reduced soil oxygen.

By avoiding these pitfalls, you’ll ensure your trees get the full benefits of mulching without the downsides.



Do not pile mulch too high around the base of the tree or touching the tree trunk or the root flare. Spread it out so that it is no higher than 10cm (4"in) and away from the base of the tree.

Why Mulching Matters for Your Vancouver Trees

At Arbutus Tree Service, we recommend mulching as a key component of tree care. Whether you’re maintaining your landscape year-round or getting ready for winter, proper mulching can help your trees thrive in Vancouver’s unique climate.

If you have questions about mulching or tree care, our experts are here to help. Contact us today to schedule a consultation or learn more about our tree care services.

For more on this topic, check out Proper Mulch Technique (pdf guide) from Trees are Good.
View full post