University research indicates you can mulch up to 6 inches of leaves on your lawn as long as you mulch leaves into small pieces.
Leaving leaves on your lawn can potentially harm your grass. While a thin layer of mulched leaves can decompose and enrich the soil, a thick layer can smother the grass and prevent sunlight, air, and water from reaching it.
Leaf residue left behind on the surface of the lawn after mulching over leaves. The tiny pieces will last a few days and eventually sift down through the turf.
Leaves have nutrients, which can be recycled into your lawn. The concern is if your leaf layer is very thick and will smother the grass. If you have just a few leaves, such as 20 percent of the lawn covered, you can just ignore them. They will blow around, settle in, and break down on their own.
Cons of mulching leaves
Too much leaf mulch can create thatch. Thatch buildup isn't good for lawns as it creates a barrier that blocks water, oxygen, and nutrients.
Leaf mulch can renew plants, but there is truth to the idea of too much of a good thing. Leaf mulch in a layer no more than one inch thick on targeted soil can moderate soil temperatures as we prep for the winter months. This protects the plants and minimizes your need for additional fertilizing at the moment.
Deep mulch is often applied as a means to control weeds and reduce maintenance, but it might actually create additional problems such as root rot, nutrient deficiencies, and toxicity. Deep mulch can also create a habitat for rodents that chew bark and eventually girdle trees.
Leave the leaves, or move them just a bit
Leaves are great for soil quality: they can suppress weeds, retain moisture, and boost nutrition. And perennial plants appreciate the extra insulation through the winter, too!
Excessive leaf matter on your lawn going into winter is bad for several reasons. First, it will smother the grass and if not removed very soon in the spring it will inhibit growth. Second, it can promote the snow mold diseases. And finally, turf damage from critters (voles, mice) can be more extensive in the spring.
Local ordinances may apply: Some cities and neighborhood HOAs have rules about removing leaves for the sake of tidiness. In this case, you should plan to rake your yard, or you could potentially face a fine.
Over time, those leaves will break down into rich, organic compost that will do wonders for improving the quality of any soil. While it's not an overnight transformation, in a few years, even hard packed clay will improve to an impressive mix of rich loamy soil several inches deep.
Simply mow over the fallen leaves. All landscapers have the equipment to mulch mow, and it is just as easy (or easier) to mulch mow than it is to blow the leaves to the curb. If you find that you have excess leaves, place the mulched leaves in your garden beds.
That's why the first number in the N-P-K on most lawn fertilizer labels is the largest. By mulching leaves instead of raking, you treat your lawn to natural fertilizer and beneficial organic matter.
While whole leaves take a longer time to break down (about two to three years), cut up leaves decompose faster (about one year) and can provide plenty of nutrients for the soil. You can use whole and/or chopped leaves in gardens and flower beds as mulch.
It's best to rake leaves while they are dry and before the frost and snow begins. Many individuals like to keep up with leaf maintenance by raking or mulching them as they fall, while others may wait until all the leaves have fallen to the ground before raking.
Leaves are truly a valuable natural resource! They contain 50 to 80 percent of the nutrients a plant extracts from the soil and air during the season. Therefore, leaves should be managed and used rather than bagged and placed at curbside to be picked up and hauled to landfills.
Dark, damp leaf piles full of insects and trash provide everything rats and mice need to survive and reproduce. These piles often include twigs and branches that enable rodents to grind down their ever-growing teeth without leaving their new “home.”
Although people often rake and bag leaves to prevent their lawns from being smothered and to make yards look better, in most cases, you're fine not moving them. In fact, many environmental experts say raking leaves and removing them from your property is not only bad for your lawn but for the environment as a well.
"If you just leave the leaves on the grass, it will exclude light. And then the grass won't be able to photosynthesize. Eventually, it would die under a thick layer of leaves," Barton said. Rake excess leaves into a landscape bed and it will turn into mulch.
One layer of leaves over mulch may not seem like a massive issue. And for the most part, it's not. But when other layers begin piling on top of the first layer, and then rain falls to create a moist pile of dead leaves, your landscape beds could develop diseases like snow mold that affects your plants.
Conversely, mulching lawns can prevent weeds and improve lawn drainage. It can also promote healthier grass. However, mulching also has some potential drawbacks. For example, if too much mulch is applied, it can smother the grass and prevent it from getting the oxygen it needs to thrive.
While the material itself does not draw termites to the area, mulch spread over three inches deep creates an inviting habitat for the pests. Layers of organic matter trap heat and moisture next to the ground. Termites use this thick mulch as shelter from harsh weather. Some kinds of mulch may even repel termites.
When Not to Mulch. Don't mulch just before major rainfall is expected. Too much rain might cause your mulch to run right off your flower beds or away from the base of a tree. You also shouldn't mulch right before a very windy day.