The Case Against Mulch Rings

It’s a common sight in the American landscape: trees skirted with a ring of mulch around their base that float in a sea of lawn.  Landscapers started the practice to prevent mowers and weed eaters from damaging tree trunks, and many arborists like the protection that mulch gives to the roots.   But listen up America:  these mulch rings have got to go.  The benefits of mulch rings have long been exaggerated, and they are just plain ugly.  Consider a few reasons for eliminating this practice.

In nature, plants happily share space with tree roots.  Why do we add the rings?

The first reason given for using mulch rings is for the convenience of lawn maintenance.  Having several feet of mulch around the base of the tree keeps mowers and weed eaters away from the trunk, preventing damage and soil compaction.  These are indeed valid benefits.  But I would first question how convenient these rings actually are.  I spent almost a decade doing professional landscape maintenance, and the rings eventually become more trouble to maintain and edge than it is to mow around the base of trees.  The truth is, it’s just not that hard to cut grass around trees without damaging them.

Forget convenience: mulch rings are downright ugly.  They make Swiss cheese out of an otherwise attractive and continuous lawn.  Why can’t the lawn grow right up to the trunk?  It’s beautiful.  Look at all the great gardens of Europe.  They never use mulch rings.  Mulch rings are another example of how we’ve sacrificed aesthetics for the convenience of our motorized tools. 

Lawn growing up to the base of trees creates elegant, park-like feeling

A client of my former firm had a beautiful lawn punctuated with large canopy trees.  We had removed nearly four acres of lawn on their property and replaced it with more sustainable gardens.  But they wanted to keep the front lawn.  Their landscapers had surrounded each large tree with a small mulch ring, making their lawn look fragmented and random.  We re-seeded lawn right up to the base of the trunks.  The result was staggering.  The space felt continuous and park-like. 

But isn’t mulch good for trees?  And doesn’t lawn compete with the trees for nutrients?  Mulch is indeed good for trees, and lawn does compete with trees for water and nutrients.  The problem is that the feeder roots of trees extend much beyond the mulch rings.  In fact, feeder roots can actually extend 20-50 feet beyond the dripline of the tree.  The tiny ring of mulch around the tree base covers only a fraction of the overall area of the roots of a canopy tree, negating much of the benefits of mulch.

What’s worse is that mulch rings encourage over-mulching at the base of trees, one of the worst things you can do for your tree.  The area where the trunk of the tree hits the ground is called the root flare. When you bury the root flare under mulch or dirt, it encourages the roots to grow upwards instead of outwards.  Roots that grow up are especially dangerous, as they often wrap around the trunk and girdle the tree.  If you have a trees buried under a volcano of mulch, it is gasping for air.  Dig it out and expose the flare.  

Native heuchera growing with oaks, Pierce's
Woods, Longwood Gardens

 Anytime you plant trees in lawns or planting beds, there is, of course, extra competition for water and nutrients.  Good basic garden maintenance—watering, thin applications of compost, feeding—will allow both to peacefully coexist.  Spraying compost tea over your lawns is a wonderful way to give both your lawn and the tree rich microbial stimulation without mulch.  Harvard's compost tea program is especially inspiring method for organically feeding both lawn and trees.

When it comes to trees in planting beds, I am a huge advocate of planting right up to the base of tree trunks.  Arborists tend to discourage this practice, but if you’ve ever walked through a forest, you’ll notice literally hundreds of plants happily sharing root space with trees.  Use plants (particularly native herbaceous species) that have evolved to grow on woodland floors.  Some of these plants actually have symbiotic relationships with tree roots.  Moreover, the aesthetic benefits of planting right up to the trunk of the tree cannot be overstated.  It’s incredibly beautiful, and with regular maintenance, does not have to pose a threat to trees.

Get rid of those mulch rings, and let lawn or plants grow right up to the base of trees.  Your lawn or garden will look a million times better for it. 

The beautiful effect of Trachystemom and Euphorbias growing right up to
the trunk of this holly at the garden of Ching-Fang Chen in McLean, Virginia.