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.”