If your springtime landscaping routine involves piling mulch around your trees, you’re doing more harm than good. Yes, mulch around trees is absolutely ubiquitous everywhere you go, but years of doing this can quite literally strangle the life out of a tree due to an issue called root girdling. We can correct this problem by performing a root collar excavation.
Why You Shouldn’t Mound Mulch Around Trees
Think about trees in the forest. Other plants grow around the base. There may be a layer of leaves, twigs, and other debris that breaks down over time and enriches the soil, but there isn’t a big mound of mulch or dirt around tree trunks—yet somehow this has become a common practice in landscaping.
Piling mulch or dirt around a tree trunk suffocates it because the entire trunk is meant to be above ground, in the dry air. When, instead, the trunk is kept moist, its cells become damaged. This is bad news for the rest of the tree—when the base is ailing, it can’t transport nutrients and water as efficiently as it should. You may start to notice that the tree’s leaves are smaller from one year to the next and that they drop off earlier than they should, not knowing it’s the mulch you put at its base each spring that’s causing the problem.
With all that moisture kept near the trunk, your tree’s roots will start growing up and around the trunk rather than under and away from the tree. This is the root girdling we mentioned above and it further compounds the problem. Now, the cells at the base of the trunk are damaged from moisture and the tree is effectively strangling itself. This stress makes it susceptible to disease, insects, and fungi.
How Root Collar Excavation Helps
If you guessed that the solution for root girdling is to remove the mulch or dirt around the trunk, you’re correct—but there’s a very specific way to accomplish this goal. Using a shovel or spade can damage already-stressed roots; instead, we used compressed air to avoid harming the tree.
Once we’ve exposed the entire trunk in order to keep it dry, we carefully rearrange your tree’s roots. If you do a lot of gardening, you know that before planting anything; you need to tease apart the roots so they don’t grow into a tangled ball. The same principle applies here, on a much larger scale. Some roots will be pruned, while others will be repositioned to encourage them to grow away, rather than around the tree. When the process is complete, your tree’s health will be restored.
Preventing Girdling Roots
Does this mean you shouldn’t use mulch at all? If you like the look of mulch, you can use it, but only a thin layer—don’t pile or mound it around your trees. The common saying among arborists is “your trees shouldn’t look like telephone poles.” In other words, the part of the trunk that flares out and spreads as it reaches the soil should be visible.
Or, even better, grow some native shade-loving ground cover plants under your trees instead for a natural look that replicates how trees grow in our local forests. We’re happy to offer suggestions!
Schedule a Property Inspection
Do you suspect that one or more of your trees may need root collar excavation? Learn more about us, then schedule a property inspection today by calling 610-840-2655 and our certified arborist will come out to determine whether your tree is experiencing root girdling.