Choosing the Right Mulch

Ah, the delicious smell of mulch is in the air here in Philadelphia. Driving down 202 at 7am on any given weekday, a caravan of landscape trucks filled to the top with mulch can be seen making their way to homes around the Main Line.

Many homeowners choose to mulch their landscapes in the spring for season-long weed control. A sharp edged garden bed and fresh mulch also look fantastic and contribute to a vibrant landscape. Did you know there are a multitude of other benefits that annual mulching provides?

Healthy plants and trees start with healthy roots. Healthy roots start with healthy soil!

Mulch doesn’t only look great and suppress weeds, it also:

• Regulates soil temperature, protecting your trees and shrubs from major temperature fluctuations (we have a 53° temperature change in the 5-day forecast this week).

• Mitigates evaporation and water loss, which is especially important in July and August when we regularly have temperatures in the high 90s with periods of drought.

• Prevents soil compaction by providing a barrier between your soil and foot traffic (yes, just walking on your soil is enough to compact it!), garden tools such as wheel barrows, and heavier equipment or machinery. Mulching also creates a barrier between your trees and plants and any lawn equipment that may injure their roots and trunks.

• Improves soil composition by breaking down slowly and feeding the living organisms in your soil. This increase in biodiversity is crucial because the presence of earth worms and microorganisms helps to create the ideal loamy soil structure which is hard to come by in our heavy clay soil region!

• Prevents erosion by absorbing excess storm water and water runoff. Heavily compacted soils flood often because they do not have any space to absorb water.

• Nourishes the soil by replacing key nutrients and organic matter that have already been absorbed by the plant. This can also be achieved with annual deep root feeding and fertilization.

Here is a great Penn State resource on the many benefits of proper mulch: https://extension.psu.edu/mulching-landscape-trees

Which Kind of Mulch is Right for You?

For new garden beds, or landscapes that are heavily planted, leaf mulch will give you the soil structure, nutrients and protection needed for plant health.

Alex and I recommend the leaf mulch from Underdog Landscape Supply in Conshohocken. They are both wholesale and retail, so you can order directly from them for home delivery or you can ask your landscaper about on-site pickup.

When we purchased our home in 2015, our landscape was entirely grass with the exception of a single crepe myrtle tree and a yew hedge. We’ve removed about 60% of the grass for new garden beds and over the last six years have applied Underdog’s leaf mulch annually or bi-annually (spring and fall applications). Our soil has changed incredibly from densely compacted clay to the ideal light, airy loam structure and our trees and plants are thriving!

For landscapes with hardy foundation plantings that are already in good health, wood mulch is a good choice. Wood mulch typically provides longer lasting control than leaf mulch because it takes longer to break down.

Here is a helpful article if you are unsure which kind of mulch is right for you: https://simplifygardening.com/leaf-mulch-vs-wood-mulch/

Whatever kind of mulch you and your landscaper choose, it is crucial to apply mulch properly or you can cause serious harm to your trees and plants! Although you might be tempted to heap on piles of mulch to reap its myriad benefits, do not apply more than 2-3” of mulch to your landscape. This is particularly important when mulching around trees.

The trend of piling mulch in a mound around the trunk of a tree is referred to as “volcano” mulching and is guaranteed to slowly kill your trees. The constant moisture against the trunk of the tree causes rot, bacteria and fungal infections, insect infestations and upward root growth that will eventually girdle the tree.

Take a look at the base of the trees the next time you go for a walk or hike through the woods. You will always see a visible trunk flare with shallow roots. This should be mimicked in your own landscape.

Oh no! I just realized my trees have volcano mulch. What can I do?

Don’t fret, there is still hope for your tree. If it is a new planting, or the volcano mulch has been applied in the last year or so, you can try to manually remove the mulch from the base of the tree using your hands or a small trowel.

If the mulch does not come away easily from the trunk, the tree has likely already begun winding its roots upward and professional help is required. Champion Tree uses compressed air to blast away excess mulch. At that point, once the roots are exposed, we can determine whether the roots have girdled the tree and which need to be cut for the health of the tree.