How to Compost Your Grass Clippings

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grass clippings and leaves in a compost pile

Composting is more than a trend. It is estimated that around 30% of our annual waste could be redirected back into the Earth through composting. This includes the waste you produce right in your backyard — your grass clippings.

Grass clippings are a great source of nitrogen, making them an ideal component of a compost pile or bin. A substantial amount of yard trimmings — more than 22.3 million tons per year — are already being composted by Americans today. 

You can make a difference by composting your grass clippings, too. Read on to learn more about how to compost grass clippings.

  • What is composting?
  • Why is composting important?
  • Why compost grass clippings?
  • How to compost grass clippings
  • What else can go into my compost?
  • What not to put into your compost
  • Remember to balance carbon-nitrogen levels
  • Frequently asked questions about composting

What is composting?

Composting is a form of recycling, where you take organic matter — such as food scraps, dry leaves, and grass clippings — and help them decompose into a nutritious fertilizer. You can participate in industrial composting by signing up for your local green waste bin program, or you can reap the benefits of creating your own compost pile at home. 

Composting helps organic materials decompose through aerobic decomposition — a form of decomposition where organic matter is being broken down into compost by microorganisms that need oxygen to survive. 

This is much better for the environment compared to anaerobic decomposition — a form of decomposition where organic matter is being broken down by microorganisms that do not need oxygen to survive. This is the type of decomposition that occurs in landfills since so much trash is being piled up, little oxygen is able to move through the matter. 

Why is composting important?

Anaerobic decomposition creates biogas (50% methane and 50% carbon dioxide) as a byproduct, which is why landfills are the third-largest source of methane emissions created by humans. By composting your grass clippings, you’ll be helping to significantly reduce the amount of waste going into landfills and the number of emissions being created.

Why compost grass clippings?

Grass is a free resource that can either be recycled back into the Earth, returning water and essential nutrients to the soil, or it can be trash bagged and thrown into a landfill, generating more fossil fuels and damaging the environment.

There are countless benefits to composting your grass clippings, including:

  • Improves the health of the soil with nutrients
  • Improves aeration in the soil
  • Reduces unnecessary waste that ends up in landfills
  • Cuts down on landfill methane emissions
  • Lowers your carbon footprint
  • Reduces the need for pesticides
  • Reduces the need for synthetic fertilizers
  • Prevents and controls plant diseases
  • Promotes the soil ecosystem

Overall, composting is an easy way to take better care of the environment. Composting is a habit that gives back, helping you get rid of your yard waste and providing you with free, organic fertilizer to help your plants grow strong and healthy.

One thing to note: Do not add grass clippings that have been treated with herbicides to your compost pile. They can (and should) be composted back into the lawn, however.

Who should compost?

People of all ages and backgrounds can learn how to compost and reduce their carbon footprint. Whether you live in a house or apartment, read on to learn how you can get started with composting.

How to compost grass clippings:

  • Grasscycling
  • Pile composting
  • In-ground or trench composting
  • Container composting
  • Vermicomposting
  • Mulching

Grasscycling

Grasscycling is the easiest way to make use of your grass clippings — you just leave them on the ground after you’re done mowing. Grass clippings are small enough to decompose without piling up and becoming thatch, and by leaving them you reduce your lawn’s need to be replenished with fertilizer. Grasscycling will cut down 30%-38% of your time spent mowing because you won’t have to worry about bagging and transporting the grass clippings. 

Pile composting

Large pile of compost with a wheel barrow next to and i sign stuck in it that reads "Compost"
Oregon State University | Flickr | CC BY-SA 2.0

If you can’t remove your lawn mower’s bagging attachment, or don’t like the look of fresh grass clippings being left on the lawn, you can still compost them. Pile composting is easy — just find an area away from your home and begin a compost pile. This is a great no-frills way for people with more space to start composting. 

Compost piles should be at least 4 square feet in size. Anything smaller will take much longer for the compost to decompose. 

Pick a location

  • Find a secluded area away from where you or your neighbors might smell the compost.
  • Place it near the garden to ease transport back and forth.
  • Ideally, it should be placed in a more shaded area to prevent it from getting dried out.

Add the ingredients

  • Layer one: Spread coarse plant material, such as twigs and branches.
  • Layer two: Add 6-10 inches of fine plant material, such as dry leaves, fresh grass clippings, and kitchen scraps.
  • Layer three: Put 1 inch of soil or manure.
  • Repeat layers two and three until the compost pile is about 5 feet tall. 
  • As you’re adding layers, add light amounts of water to help jumpstart decomposition.
  • Optional: Cover with a plastic tarp. 

In-ground or trench composting

Trench composting is a form of composting where you bury food scraps in a trench in your garden. With trench composting, you can compost taboo materials such as meat, dairy, and cooked foods without worrying about attracting pests. You also can trench compost pet feces, as long as the garden is not for edible crops. After you’re done filling the trench, cover it with your leftover grass clippings as a mulch to keep everything in place.

How to make a trench compost:

  • Dig a hole 18-24 inches deep in your garden. The hole can be as wide or long as you want, but generally, a shovel’s blade width works best. 
  • Fill 6 inches of the trench with food waste and moist organic materials. Fill the trench with soil, covering it with at least 12-18 inches of soil.
  • Cover with a layer of organic mulch (your grass clippings). 

Container composting

plastic barrel on a wood frame for composting
Karen and Brad Emerson | Flickr | CC BY 2.0

Container composting is similar to pile composting — you just layer your grass clippings in amongst other organic materials, turn regularly, and wait. Container composting is great for homeowners with limited yard space or who live very close to their neighbors.

There are many options for both indoor and outdoor container composting. Wire fencing, cement blocks, and barrels are popular options for outdoor compost structures. Indoor composting is usually done in a plastic container — there are now plenty of options out there that help deal with compost smell, as well. 

You can even get a compost tumbler, which is more expensive than most containers, but will have a faster compost turnaround due to the ease of turning. 

The composting process here is the same as pile composting. Since indoor compost bins will likely be much smaller in size, aim for a 2:1 brown to green ratio. 

Vermicomposting

hand holding a small worm surrounded with dirt
Vanessa Vancour | Flickr | CC BY 2.0

Vermicomposting is a form of container composting using a worm composting bin that is inexpensive and easy to maintain both indoors and outdoors. If you have a small yard, you can keep it out of the way on a patio or in a shed. If you have the space and don’t mind some wiggly roommates, it can be kept anywhere inside, as well. 

You can build it yourself or buy a bin specially designed for vermicomposting

Mulching

Mulching your grass clippings is another easy way to compost them, especially if your lawn mower has a bagging attachment. 

Mulching has several benefits:

  • Regulates soil temperature.
  • Conserves moisture.
  • Reduces weed growth.
  • Prevents soil erosion.

Mulching grass clippings is easy:

  • Let the clippings dry.
    • Wet grass clippings will stick together and mat down the soil, preventing nutrients and oxygen from reaching the plant roots. 
  • Sprinkle a thin layer (1 to 2 inches) of grass clippings on top of and around the plants in your garden bed.
  • Add more as they decompose.

Pro Tip: Don’t mulch your grass clippings if your lawn has been recently treated for broadleaf weeds (such as dandelions) with an herbicide. 

What else can go into my compost?

infographic showing the materials used in composting. Including the most common brown and green options.

These are the essential ingredients that make up your compost:

  • Organic matter
  • Carbon
  • Nitrogen
  • Water
  • Microorganisms
  • Macroorganisms
  • Air

Organic matter is made up of two types of materials: brown and green.

  • “Brown” materials: newspaper, dead leaves, sticks, toilet paper rolls, etc. These provide a source of carbon.
  • “Green” materials: kitchen scraps, grass clippings, coffee grounds, and similar items. These provide a source of nitrogen.

Water helps the organic matter break down and decompose more quickly. Microorganisms (bacteria, fungi, etc.) and macroorganisms (worms, bugs, etc.) help with the decomposition process by breaking down the organic material into compost. Air and nitrogen are essential for microorganisms to survive, which is why it’s important to turn compost frequently and pay attention to the carbon-nitrogen (C/N) ratio. 

What not to put in your compost:

  • Pet waste (chicken, cow, and horse manure is fine) 
  • Black walnut tree leaves/twigs
  • Coal or charcoal
  • Diseased plants
  • Grass trimmings that have been treated with herbicides or pesticides

Additionally, avoid composting dairy products, grease, or meat trimmings because these will attract pests and rodents and create an unpleasant odor. 

Remember to balance carbon-nitrogen levels

Carbon and nitrogen are essential for the survival of the microbes that will break down your compost. Carbon is a source of energy, and nitrogen is a source of proteins, enzymes, and amino acids. 

What is the ideal carbon-nitrogen (C/N) ratio?

The ideal C/N ratio is 30:1, meaning 30 parts of carbon per 1 part of nitrogen. 

What happens if the ratio is off?

Too much nitrogen will lead to pungent odors, and too little nitrogen will starve the microbes and cause delayed decomposition. 

Some “brown” organic materials have higher amounts of carbon than others.

Brown MaterialC/N
Dead leaves30-80:1
Pine needles90:1
Sawdust100-500:1
Bark100-130:1
Newspaper560:1
Corrugated cardboard560:1

You can calculate your overall C/N ratio by also taking into consideration the levels of your “green” nitrogen-rich sources.

Green MaterialC/N
Food scraps15:1
Grass clippings18:1
Coffee grounds20:1

Frequently asked questions about composting

1. How often should I turn my compost?

Be sure to turn your compost pile frequently. 

Aim to turn:
Weekly during the summer
Monthly during the winter
Whenever you add grass clippings, to prevent them from matting

You’ll know it’s not being turned enough because it will begin to smell like rotten eggs. 

2. How often should I water my compost?

The compost should be moist, like a slightly wet sponge. You’ll know your compost is too wet because it will start to get slimy and smell bad. Depending on where you live you may have to add water occasionally, especially during hot, dry periods. Make sure your compost has good drainage to prevent it from being soaked. 

3. How long until my compost is ready?

A lot of factors go into the decomposition time frame. The items you’re composting and the method you choose greatly affect when the compost will be ready to use. Pile composting can take between two months and two years, while container composting can take as little as two weeks. If you don’t turn your compost regularly, it will take even longer. To speed up your compost, try shredding and chopping items before adding them to the pile or bin. 

4. How can I tell the compost is ready?

The compost is ready to be used when the bottom layers of organic material appear dark and rich in color.

5. Will my compost smell? Will it attract pests?

If you properly maintain your compost pile or bin, you shouldn’t have to worry about smell or unwanted critters digging through it. Make sure you’re not adding taboo items to your compost pile, such as meat scraps, grease, bones, or eggs.

6. When should I start composting?

You can begin composting at any time of the year. If you want the compost to be ready for spring planting, try to start in the summer or fall before. 

Need a hand taking care of your lawn? Depend on a Lawn Love pro for all your landscaping and lawn care needs.

Main Photo Credit: PublicDomainPictures.net | CC0 1.0

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