Mulch your trees like a pro: Apply mulch the right way

In our last post you will have discovered just how beneficial mulch is for trees, so you’re probably dying to get your hands on some mulch and spreading it under all the trees in your garden. Hold onto that enthusiasm, but do read this first.


  1. Before you put any mulch down, check the soil drainage around your trees. If the soil doesn’t drain well, adding mulch may do more harm than good. Although most mulches are versatile and shouldn’t cause any problems, some plants and trees will benefit even more from slightly acidifying mulch such as pine bark.
  1. If the area drains well you can proceed to lay down a layer of mulch around 5cm to 10 cm thick. The coarser the mulch, the thicker you can make it. Spread the mulch out to reach the edge of the tree’s crown and beyond. Remember that the root structure of the tree extends over a very wide area and that’s what the mulch is there to protect.
  1. Before laying down a new layer of mulch, check the old mulch. If it’s become compacted over time, use a rack to break it up and refresh it.
  1. Pull the mulch away from the tree trunk to create a doughnut hole to expose the base of the trunk. Piling mulch up around the base of the tree may suffocate the tree; increasing heat and moisture which give rise to pathogens and rot.

This is called a ‘mulch volcano’; an excessive pile of material applied around the base of the tree. Any arborist will tell you that mulch volcanoes should be avoided if you want a healthy tree.

In the image below you’ll see two trees. The tree on the left has been mulched correctly while the tree on the right is an example of the dreaded ‘mulch volcano’!


Image from Mulch This Over! by Dr. Richard L. Bitner

Image from Mulch This Over! by Dr. Richard L. Bitner


Some things to look out for:

  • Exercise caution when using mulch on wet soils. Excessive moisture in the root zone can stress the tree out and may lead to root rot.
  • Piling mulch against the base of the trunk can stress stem tissues and lead to problems with pests and disease. It creates an ideal environment for rodents who may chew the bark and damage the tree.
  • Mulch that includes fresh grass clippings can affect the pH level of the soil. This in turn could lead to nutrient deficiencies or toxic build-ups.
  • Thick, matted mulch makes it harder for water and air to reach the roots. If you’ve noticed that the mulch around your trees has become compacted, use a rake to loosen it up and improve the airflow.

Mulch is marvellous stuff, not only for trees, but for all the plants in your garden. You can easily get mulch from your local nursery or garden centre, or give Brands Tree Felling a call. Our nutrient rich, organic mulch is guaranteed to give your trees everything they need to grow strong and healthy.