Fallen leaves can cause harm to your yard in the following ways:
- Smother grass.
- Cause fungus that kills lawns.
- Invite pest insects and rodents.
- Cause lawn flooding and promote improper drainage.
Raking leaves is a good way to eliminate these risks, but you’re missing out on the positives those leaves can provide. Rather than bagging and trashing leaves, consider mowing fallen leaves to feed your yard, using leaves as garden mulch, or composting your autumn leaves.
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Is it Bad for Your Lawn to Not Rake Leaves?
In small quantities, fallen leaves are rarely bad for your lawn. However, if there is a large amount of fallen leaves on your lawn (10–20% of the grass in an area is covered by leaves) it is harmful to your lawn to not rake leaves. Like all plants, your lawn grass needs to receive air, water, and sunlight—drifting leaves can deprive your lawn of all these things.
A small dose of leaves, or leaves chopped into small pieces, break down easily and feed your soil, but a blanket of leaves forms a barrier that chokes the life out of the grass and plants beneath.
Negative Effects of Leaves on Your Lawn
Depending on the climate and region you inhabit, not raking or otherwise managing fallen leaves can have different negative impacts on your lawn and garden. It’s important to know what can happen if you let those leaves stay where they lay.
Smother Grass
A carpet of dead leaves can block sunlight from reaching your grass. This kills patches of grass in your yard, making it easier for shade-loving weeds to invade your lawn.
The effects of not raking leaves can be seen quickly in areas where grass grows year-round. If left on top of the grass for a few weeks, leaves will smother the grass. In regions with snowy winters, the leaves will remain beneath the snow all winter, only to be revealed during the thaw. In spring, the leaves will smother your grass as it tries to green up.
Invite Fungus
Wet leaves are a lawn management challenge on their own. Whole, dead leaves decay slowly and trap moisture, often attracting gray or orange fungus that can spread to lawn grass and garden plants, killing them. Grass afflicted by fungi like brown patch and dollar spot can appear yellow, brown, or have a wet, slimy feel. Unraked leaves can contribute to these diseases, or even cause them.
Fungus invasion due to dead leaves is often found in cool, high-moisture climates. Regions, where fall leaves are buried in snow and then exposed to spring thaws, create the perfect conditions for a “snow mold” fungal invasion.
Attract Pest Animals
Drifts and layers of unraked leaves are an invitation for insects, rodents, and reptiles, which use the leaves as shelter. In warm regions, leaf piles and waterlogged dead leaves create breeding grounds for gnats, mosquitos, and other insects. In cooler regions, mice and voles will tunnel under dead leaves.
If leaves have created a welcoming environment for pests near your home, there’s a much higher chance these animals will invade your home, especially as the weather cools. The mice living in your leaf litter are likely to try to move into your home as the first snowfall approaches.
Contribute to Lawn Flooding
Unraked leaves on a lawn often clog outdoor drains, which leads to oversoaking of your lawn, damaging it. Leaves clogging drains, gutters, and natural drainage passageways can flood your garden, your basement, or turn your lawn into a mud pit. The best course of action is to manage your leaves and prevent flooding disasters.
How Long Can Leaves Stay on Grass?
Leaves can stay on grass for 3–4 weeks without causing any lasting harm. You don’t have to bust out your rake as soon as the first leaves fall. Be pat ient, as many large trees lose their leaves over a period of several weeks. It’s perfectly fine to let all the leaves fall, then begin your leaf management strategy.
Are Dead Leaves Good for Grass?
Dead leaves can be very good for grass if they’re properly mulched. Whole leaves decompose slowly, trap moisture, block sunlight, and harbor fungus. If those same dead leaves have been mowed over a few times and chopped to bits, they won’t block sunlight and will decompose quickly, returning nutrients to the soil.
How Long Does it Take Leaves to Decompose?
If they are left whole, leaves will take 6–12 months to decompose. This means that if you don’t manage your leaves then as soon as one year’s leaves are rotting away, new ones could be falling. Mowed, mulched, or composted, leaves can decompose in as little as 3–6 months, returning nutrients to the soil much faster.
Benefits to Not Raking Leaves on Lawn
Raking and bagging isn’t the only option for dealing with leaves. Because leaves contain nutrients and decompose into natural fertilizer, your fall leaves can be used to benefit your lawn and garden.
Feed Your Lawn by Mowing Leaves
If you’re really sick of raking leaves, you can ditch the rake and benefit your grass at the same time. Simply mow over your fallen leaves 3–4 times with a mulching lawnmower or a standard lawnmower. You don’t need to bag the leaves or change the blade height of your mower for this.
Mowing the leaves will chop them into small pieces which will keep them from smothering your lawn and prevent them from drifting and breeding fungus. The mowed leaves will decompose in a few months, giving your lawn a boost and saving you the trouble of raking.
Use Leaves as Mulch
Leaves are an excellent natural mulch. They decompose over time, feeding your soil, and a 3–4-inch layer of leaves in a garden helps suppress weeds. If you want to try out this natural mulch, you can rake whole leaves into your garden, or use a leaf blower to blow mowed and mulched leaves into your garden.
Add Leaves to Compost
Leaves are an excellent compost additive. They decompose quickly and contain nitrogen, calcium, and magnesium, as well as traces of phosphorus and potassium. These are all nutrients plants crave. Tossing leaves into your compost helps you create powerful fertilizer without spending a dime.
Is it Better to Rake Leaves or Leave Them?
If you have enough fallen leaves on your lawn that 10–20% of your grass is covered, you need to do something with those leaves. If left alone, those leaves will smother your grass, invite pests, and breed fungus that can spread to your lawn and garden. However, you don’t have to rake your leaves. You can simply mow them where they lay to help them break down fast and fertilize your grass. Otherwise, you can use leaves as mulch or add them to compost. These are all better alternatives to the traditional practice of raking leaves and throwing them out.
