Chopped into bits, those leaves become fast-decaying mulch that adds organic matter and nutrition to feed the grass. Unless the layer is very thick, chopped leaves don't cause thatch as many people think.
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.
Research has shown that mulching leaves into the turfgrass canopy increases organic matter at the soil surface, but does not contribute to the direct buildup of thatch (Horton, 2014).
Clippings consist mostly of water, and the remaining tissue is quickly broken down through microbial activity. Grass clippings may add to an existing thatch problem, but as long as the lawn is mowed regularly and a mulching mower is used, mulching lawn clippings into the lawn will not cause thatch buildup.
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 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.
“Using a mulching mower to not only mow but to mulch leaves will help keep your lawn properly trimmed, but also accelerate the rate of leaf decomposition into beneficial soil organic matter,” says Dan Sandor, who is also an expert in turfgrass science at Virginia Tech.
In addition to nourishing your lawn, mulching grass clippings and leaves when you mow saves time, money and is better for the environment. Dealing with lawn clippings or raked up leaves can often be a painful and laborious process. Mowing, bagging and disposal takes a lot of time out of your day.
Thatch Buildup Occurs When Microbial Activity is Lacking
Soil compaction – Limits air, water, and microbial movement in the soil. Low soil moisture – Microbes need moisture to thrive and break down organic matter. Excess pesticide or fungicide use – Kills off beneficial microorganisms that help with decomposition.
A layer of mulch can fight off weeds and some mulch can help keep moisture in the ground, but too much can prevent air and water, especially from a light rain, from getting to the roots. It can also trap moisture against the trunk, leading to trunk rot, fungus and disease which can prematurely kill your tree.
Lawn clippings don't cause thatch.
Grass clippings are mostly water, so as long as you mow regularly at the right height, they will break down and disappear rapidly.
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.
To get a level cut and effectively shred the leaves, the ideal height for leaf mulching is 2.5 to 3 inches. The mower deck shouldn't be too high or too low. Be mindful of the blade you're purchasing. Like their namesake, gator blades should be sharp and pointy like alligator teeth, not blunt and square.
Manually raking thatch out
Manually raking your lawn is by far the cheapest option and a fairly quick way of removing thatch. You can pick up a rake for next to nothing.
Run a core aerifier over the lawn several times in different directions to break up compacted soil as much as possible. You can also allow cores to sit on the surface and crumble apart over time. This "top dresses" the grass with soil containing desired microorganisms that will work at decomposing thatch.
When to Dethatch Your Lawn. The best time to dethatch your lawn is when it's actively growing and the soil is moderately moist. For cool-season grasses, that's early spring or early fall. For warm-season grasses, dethatch in late spring through early summer (after the second mowing).
Mulch that is too high or too close to the trunk can cause problems that damage your tree over time. Too much mulch can… Smother the tree's roots, thus starving them of needed oxygen. In search for oxygen, the roots will often grow up through the mulch causing them to “girdle” around the trunk and cut off water supply.
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.
To put it simply, mulching the grass clippings is the best option. That's because the grass clippings are full of nutrients, and as they decompose, they will return the nutrients to your soil.
Can you mulch too many leaves? It's possible to over-mulch leaves. If the leaf mulch is thick enough that it's blocking and smothering the grass, that's a problem. Ideally, you should still be able to see the grass when you're done mulching to ensure its ability to continue growing.
Used as garden mulch, shredded leaves help avoid fluctuations in soil temperatures that can damage plant roots. As mulched leaves decompose, they work as a soil amendment, adding organic matter and improving soil. Mowing leaves instead of raking also helps to reduce landfills.