Hi Suzanne,

Mulching your tree is a great way to prevent future damage from string trimmers and lawn mowers! To properly mulch your tree, you'll want to remove the sod and then cover the area with 2-4" of mulch, being careful not to pile the mulch up against the trunk of the tree (leave about 6" between the tree trunk and mulch so that the tree's root flare can still receive adequate oxygen). Here is an info sheet on mulching trees specifically, and here is a fact sheet on using mulch in your home garden more generally.

With regards to helping the root that is already damaged, unfortunately there is nothing that you can do. However, with proper care moving forward and preventing any additional damage, the tree should be able to recover.

Thank you, and feel free to reach out if you have additional questions!

Also, would you mind sharing your zip code? We are collecting this information so that we can better serve our local gardening community!

Caitlin W. and Jessie A.

Hi Suzanne, 

It is recommended that established trees be mulched under the canopy of the tree.  This link provides good details and photos to guide you.  https://extension.psu.edu/mulching-landscape-trees

The grass should be removed from the area you plan to mulch, and it is recommended to do this by hand to avoid damaging the roots.  This link talks about preparing for underplanting, but the same method applies to preparing for mulching.  https://extension.psu.edu/underplanting-trees-respect-the-roots 

Removing the grass around a large tree is going to be a lot of work but it's recommended and it will help the tree.  You'll also need to watch for grass growing back -- it will be a maintenance job. 

Good luck, 

Trish G