Volcano mulching continues to be an epidemic in the landscape. This got me to thinking, if we cannot get people to avoid mounding mulch up against their trees’ trunks, maybe we should do without mulch all together.
Gasp! I love fresh mulch and I do believe I am addicted to pine fines. I love the clean look of a fresh layer of pine fines and I love the way it feels to work it into a clay-rich garden. I understand the appeal of mulch. But let’s look at why we mulch around trees:
“We are protecting the tree and any above-surface roots from the mower and string trimmer.” That is great, but if the mulch is smothering the tree and inviting pests, disease and stress, then the protection is for not.
“We want to protect the drip line of the tree.” Let’s address the old belief that tree’s roots only reach as far as its drip line. Not true! As quoted in Arborist News (1) Tree root systems extend out 2–3 times the drip line, (2) most roots are in the top foot (30.5 cm) of soil, (3) roots extend out about 1.5 times the height of the tree and (4) more than 60 percent of the absorbing root system is beyond the drip line.
“Adding several inches of mulch each year is good for the tree and smothers out weeds.” Not really. As we just read, most of a tree’s roots are in the top foot of soil, so adding inches upon inches of mulch year after year only buries the roots, causing the tree stress.
Alternatives to mulch:
If you want a lawn, let it grow up to the tree. Keep your lawn tall to suppress weeds and reduce the need for watering and gently pull any unwanted lawn away from the base of the trunk.
A better option: plant a carpet of groundcover. Sweet woodruff is easy to grow, easy to pull where it is not wanted, has shallow roots and is pretty hardy. In the shade? Opt for pachysandra.
Sedges. Ever see an oak out in a field of grasses and sedges, the breeze softly blowing? It’s stunning. Follow nature and replace mulch with native grasses and sedges.
Let it go. The less we disturb the soil around the tree, and remember those roots are going way beyond the drip line, the healthier our trees will be.
Sounds like more work. Possibly, yes. But I would rather invest the time in an alternative to mulch that risk the health of a 30+-year-old oak or maple.