When To Act
While a few leaves won't harm your lawn, you need to remove them when they begin to pile up. Fallen leaves can smother turf, blocking sunlight from reaching grass blades and limiting air circulation, which can lead to turf diseases. The weight of leaves can actually prevent grass from growing properly. A leaf layer also keeps soil moist, which can cause turf roots to rot if the soil stays wet long enough. In short, ignoring leaves on your lawn isn't an option – it could kill your grass.
Learn about the signs of common lawn diseases here if you think you have left leaves on the the lawn too long.
In general, it's time to deal with leaves when you can't see the top half of the grass blades or when they cover more than a third of your overall lawn. If a deep cold snap triggers leaf drop that happens quickly over a few days, you can wait until the lawn is nearly covered with a single leaf layer. Just don't allow grass to remain obscured with fallen leaves for more than a few days.
Whether you opt to rake or mow over leaves, it's always better to act before rain arrives and transforms dry leaves into a soaked, clumping mat. Wet leaves won't chop well with a mower, and they tend to clog rakes and leaf vacuums.
How To Avoid Raking
You can skip raking completely by mowing over leaves and chopping them into small pieces. If you plan to compost leaves, chopping them first speeds up decomposition. Use a grass catcher to gather leaves as you mow over them.
You also can allow leaf pieces to decompose in place on the lawn. To do this, chop leaves into dime-size pieces. Depending on how large leaves are and how deep the layer is, you may need to mow over them several times to chop them small enough. After mowing, you should see roughly 50 percent of the grass through the leaf pieces. The more grass you see, the more quickly those leaf pieces will decompose.
As the leaf bits settle onto soil between grass blades, microbes start the process of decomposition. Providing a nitrogen source, like that found in a winterizer or fall-timed lawn fertilizer, will help soil microbes break down leaves faster. Allowing leaves to decompose in place ultimately enhances the soil beneath your lawn, adding organic matter, which leads to a healthier, thicker lawn.
Thick, leathery leaves won't decompose as well and should be gathered with a bagger attachment and added to a compost pile or used as mulch.
Downsizing the Pile
If you need to gather leaves and set them out for community yard waste pickup, plan to reduce leaf volume – and the number of yard waste bags you need to use. Use a leaf vacuum with a shredder feature to chop leaves, or mow over them and use the grass catcher attachment on your mower to capture leaf bits.
When considering a leaf blower/vac that offers a shredding function, examine the reduction ratio. If the product has a 10:1 reduction ratio, that means it converts 10 bags' worth of unchopped leaves into one bag. For small areas, a handheld leaf vac works well. To deal with a large lawn, you might want to rely on a mower with a grass catcher to gather chopped leaves.