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How to Compost Leaves

Medically Reviewed by Poonam Sachdev on January 05, 2023

If you live in an area where trees shed their leaves in the fall, you may wonder how to deal with them once they’re all over your lawn. Do you put them in the garbage? Leave them be? Composting leaves is one of the best ways to deal with leaves every year.

What Is Composting?

Composting is the process of recycling organic matter by creating an environment for decomposing organisms, like bacteria, fungi, and worms, to thrive. When these organisms break down the organic matter, the substance left is rich in nutrients, making it a great soil additive for plants and gardens.

Composting is a great way to get rid of food scraps and lawn trimmings that might otherwise be thrown away. When these organic materials end up in landfills, they usually undergo anaerobic decomposition — a decomposition process by organisms that don’t need oxygen to survive. Because the garbage piles in landfills don’t allow a lot of air to circulate, anaerobic organisms are the only ones that can survive. 

The problem is anaerobic decomposition releases biogas as a by-product. Biogas is about 50% methane and 50% carbon dioxide. Methane and carbon dioxide are greenhouse gasses that trap heat in the atmosphere. In the U.S., landfills are the third biggest source of human-generated methane emissions.

When you compost your organic matter instead of throwing it in the garbage, you’re helping to reduce biogas emissions. Composting also reduces the overall waste in landfills and turns them into something usable.

Composting doesn’t only give your plants a boost of nutrition. It also helps reduce erosion and conserve water because compost helps your soil retain water. A 1% increase in organic matter helps soil retain an additional 20,000 gallons of water per acre. Adding compost to your soil saves you water and keeps your soil from eroding away.

Can You Compost Leaves?

Leaves are organic materials that you can compost along with other yard trimmings like leaves, twigs, and grass clippings. Dead leaves are high in carbon, which is a food source for the decomposing organisms and allows decomposition to happen.

Leaf compost benefits include general composting benefits like reducing biogas and increasing the amount of water your soil can hold. But there are other benefits too. When leaves are left on the lawn, the decomposing organisms will start to break them down. These organisms eat the carbon in the leaves, but they also need nitrogen to grow and reproduce. 

In a compost pile, the mix of carbon-rich and nitrogen-rich organic matter allows these organisms to thrive. But when the leaves are on your lawn, they start competing with the surrounding grass and plants for nitrogen, which can reduce growth. 

By gathering your leaves into a compost pile, you avoid this competition for nitrogen while also creating a fertilizer that can help your plants grow in the future.

How to Compost Leaves

Once you’ve gathered your leaves, it’s time to create your compost pile. To start, you need the right mix of “green” and “brown” materials.

Brown materials are high in carbon. These include dead leaves, dried grass, hay, straw, sawdust, branches and twigs, and paper products. Green materials are rich in nitrogen, like fresh grass clippings and food scraps. 

Your compost pile should have a ratio of 25 to 30 parts carbon for every one part nitrogen. Since most products have a mix of carbon and nitrogen, the general rule of thumb is 2 to 4 brown parts for every one green part.

If your pile has too much carbon, it can become dry and take a long time to decompose. Too much nitrogen will make your pile slimy and smelly.

Your pile also needs oxygen. While your pile will pull oxygen from the air, allowing oxygen to circulate throughout the pile will help it decompose faster. There are a few things you can do to help oxygen circulate within your compost pile:

  • Layer green and brown materials within your pile.
  • Keep the ideal ratio of brown and green materials. Too much nitrogen will use up oxygen too fast.
  • Chop your organic material into small pieces. This allows airflow and can help them decompose faster.
  • Turn your pile either manually or with an aeration system.

The right amount of moisture is also important for a healthy compost pile. You want your pile to be about as damp as a wrung-out sponge. Keeping the right ratio of carbon and nitrogen will help, but you can always add water if your compost pile starts to dry out. 

It might be tempting to throw all your leaves in a big pile and add some green stuff, but that will take a while to decompose. At any given time, your compost pile should be between 3 and 5 feet cubed. This is because to break down properly, your compost pile should have an internal temperature between 130 and 140 degrees Fahrenheit (55 to 60 degrees Celsius). 

A pile with a volume of less than 3 feet cubed will have a hard time holding heat. And a pile larger than 5 feet cubed won’t allow enough oxygen to reach the center of the pile. If you have extra leaves, bag them and add them to the pile as it breaks down.

How to Use Leaf Compost

You’ll know your compost is ready to use when it’s dry and crumbly. Once it’s reached this stage, you can add it to the soil or use it as mulch.

To add your compost to the soil, spread a layer of compost between ⅜ and ¾ of an inch deep over your soil and mix it into the top 6 to 8 inches of soil. If you’re adding it into potting soil, make sure no more than 25 to 30% of the soil is leaf compost. This is because the compost may continue to break down over time, leaving you with less soil than you need.

Using your compost as mulch is another option. Mulch is a layer of organic material spread over the soil to moderate the temperature and moisture levels and to reduce weeds. 

To use leaf compost as mulch, spread a layer 2 to 3 inches deep for deciduous shrubs and trees, rosebeds, and vegetables. For flower beds, make a layer that's 3 inches deep. And a layer 3 to 4 inches deep for plants with shallow roots that like acidic soil.

Show Sources

SOURCES:
Earth-Kind: “Composting Leaves.”
Missouri Botanical Garden: “Composting Yard Waste.”
Natural Resources Defense Council: “Composting 101.”
Rutgers Cooperative Extension: “Using Leaf Compost.”
Sierra: “Composting 101: Hooray for the Black, Brown, and Green.”
University of Minnesota Extension: “What to do with lawn clippings.”

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