Mulch Volcanoes are Bad
Garden Guy’s warning about mounding up mulch around trees
- 🔑 Key Takeaways with Garden Guy
- Mounded, Volcano mulch covers bark, and weakens trees.
- The bottom section of a tree needs air and light.
- Tree bark that stays moist will rot.
- The volcano-mulched tree may be more susceptible to disease and insect damage.
- Properly applied mulch is about 2 inches deep and does not touch the base of the trunk bark.
- It looks awful. Stop it.
A mulch volcano is made by piling mulch up around the base of a tree or shrub in the form of a cone or volcano-like structure, either with or without an opening at the top.
The original purpose of creating a mulch volcano around a tree was probably for water retention and to also help protect young trees from debris and temperature fluctuations.
As far as the Gulf Coast is concerned though, this volcano mulching practice is out of control; destroying and weakening trees and large shrubs instead of protecting them.
While mulch does not provide trees with any extra nutrition, it does help to trap moisture in the soil and provide the tree with a buffer from changing temperatures. If applied correctly, mulch around a tree acts as just that, a moisture trap.
HOT TIP : Trapping moisture against bark is a recipe for a weak, diseased tree.
When mulch is piled around a large tree or shrub touching the bark, it DOES TRAP MOISTURE. In this case, that is not good.
Trapped moisture on tree bark will cause a weakening of the base of the tree and make it more susceptible to insects and diseases.
Also, I love this point made by the University of Nebraska at Lincoln: ROOTS NEED TO BREATHE! Tree roots respire.
” First, roots respire, meaning they take in oxygen and release carbon dioxide. This exchange of gases, as it is known, takes place in the upper 18 inches of soil. It’s no accident that roots proliferate in the top 18 inches because this is where oxygen is most readily available. Bring in a boatload of mulch and suddenly the lower roots no longer have access to oxygen. This leads to stressed and dying roots which in turn stresses the tree. A stressed tree has fewer defenses than its properly-mulched counterpart, leading to susceptibility to otherwise-minor insect and disease problems.” Nebraska Extension in Dodge County
“Mulch should be applied on the ground no more than 2-3 inches deep surrounding the tree at ground level and should not touch the bark,”
advises Todd Farber, Aggie Horticulturist of Garden Guy
Lastly, this mulching volcano foolishness looks awful. Stop it.
Go out and remove the mulch from around your trees. Compost the mulch or do something with it that is positive. Take the mulch down to a 2-inch level and give your tree a chance to thrive and your neighbors a break from seeing this ugliness in the landscape.