What to do with fallen leaves? Arborist Chris Watson considers the options

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Beautiful fallen leaves from the Amelanchiers growing at the Center for Urban Horticulture. Photo by Larry Howard 2007

To rake or not to rake? When asked what homeowners should do with leaves falling from trees growing in city gardens, Chris Watson, the Arborist who cares for the trees at the Washington Park Arboretum definitively stated, “It depends!”

Is the best mulch for a tree its own leaves? Or does that spread disease and pests? Chris explained:

“From a nutrient cycling perspective, ideally the leaves would be left in place where they fall.  Much like a forest, this would reduce the need for additional inputs, such as fertilizer. However, the urban situation is quite different from a forest.  We have introduced plants, soils, pests and diseases, as well as the desire for aesthetically pleasing landscapes.  Leaves blow in the wind and have the potential to clog drains.  Also, the first best management practice for most foliar diseases is to remove all leaves when they fall to reduce inoculum.

“When leaf removal is necessary, I recommend composting leaf material if possible.  The compost can then be used to amend soils around landscape plants.  If leaves are diseased, they should be composted in a way that increases the temperature to sterilize pathogens.  This is difficult to do for the typical homeowner, so it may be best to place leaves in the yard waste bin where they will be processed in a suitable manner.”

One Response to “What to do with fallen leaves? Arborist Chris Watson considers the options”

  1. Suzanne Ferris

    Who wrote this copy – Chris Watson or Tracy Mehlin? It should be clearly owned. I mean who wants advice from a ghost written expert?

    Some of the best soil is made from leaves loaded wet into big black garbage bags that get stored for at least a year …kicking the bags around in the backyard to distribute the leaf duff ( this idea came from Marian Raitz).