Liriope's Muse: How Volcano Mulching is Killing Your Trees

A lot of people find volcano mulching to be aesthetic due to its neat and tidy look, you can find it all across cities and in neighborhoods. It is most commonly found in medians, parking lot islands, yards, and just about anywhere a new tree is planted in the city. However, volcano mulching is a very destructive practice and can dramatically decrease the life of your trees. It’s like a disease of sorts, once it pops up in a neighbor’s yard it is bound to spread across the neighborhood.

Interestingly, over-mulching or volcano mulching came from the need to dispose of green industry waste (the byproducts of deforestation, building demolitions, used wooden pallets, and more.) To maintain an environmentally friendly footprint, the green industry waste is recycled into mulch. Due to these high waste volumes, there is an excess of mulch produced that landscapers are encouraged and even pushed to use. Thus, giving them motive to place as much mulch around trees as they see fit.

Why is volcano mulching harmful to trees?

Volcano mulching is harmful to your trees in many ways. When the mulch is piled high around the base of your tree, the mulch is in direct contact with the bark of your tree. This exposes your tree to constant moisture that can cause the bark to rot and separate from the rest of the tree disrupting the tree’s translocation, or movement of nutrients and water through the tree. The high mulch level can also confuse the tree into thinking it is the soil level making them produce more roots, except these roots grow directly from the bark instead of the root base. These are called adventitious roots. Adventitious roots start off as small hairlike roots that wrap around the tree at the base and take on the form of the mulch mound. These roots can eventually grow into thick roots that will choke or strangle the base of the tree ultimately killing it. However if caught soon enough, the adventitious roots can be cut and/or severed to prevent their regrowth before they completely kill the tree.

That said, mulching is an essential part of tree care and can be greatly beneficial to your tree if done accurately. It can preserve the soils moisture and prevent evaporation, regulate the soils temperature, limit the growth of unwanted weeds, protect the soil by reducing erosion and soil compaction, and can provide the soil with important nutrients.

How can I properly mulch my tree?

Begin by uprooting and discarding any weeds growing in the area that you will be mulching. Next, add a layer of mulch starting 4 inches from the base of the tree and expanding a minimum of 2-3 feet out. (or at least half of the trees canopy) With a depth no greater than 3 inches. When properly mulching a tree, it is important to make sure that the mulch is not touching or covering the tree’s trunk/stem. The mulch mound should take on the shape of a donut rather than volcano.

This Live Oak tree has had girdling root surgery to relieve pressure exerted by the roots in order to allow the tree to grow and expand freely.

If you have a tree with girdling roots contact the Eric Putnam BCMA team to get a quote and your tree the help that it needs.