The Ultimate Guide to Composting

Questions about composting?
We've got you covered.

Let’s start by breaking down the basics.

One-third of all food in the U.S. is wasted, but that doesn't mean it should go to a landfill. What can't be recovered can be recycled into a nutrient-rich soil amendment called compost.

What is compost?

Compost is a nutrient-rich soil amendment that is created through the controlled decomposition of organic matter such as food scraps, yard waste, manures, and other organic materials.  When done correctly it looks dark, crumbly, spongey and has a mild earthy smell, similar to top soil.

Combining the correct ratio of carbon-rich materials (browns), nitrogen-rich materials (greens), water, and air creates conditions for microorganisms, bacteria, fungi, and bugs to live. The movement and activity of billions of these microscopic creatures is what breaks down the organic material and heats the pile temperatures so that pathogens and seeds are killed off in the process.

Compost is often used as a soil conditioner or fertilizer in gardening and agriculture because it improves soil structure, adds essential nutrients to the soil that plants need to grow, increases water retention, and enhances microbial activity. Compost also helps reduce the need for chemical fertilizers and reduces waste by keeping organic materials out of landfills.

What are the benefits of composting?

Composting has a wide range of environmental and social benefits beyond waste reduction. In addition to the environmental impact like increasing water retention, and suppressing plant diseases, industrial scale compost operations can generate twice as many jobs as landfilling and seventeen times as many as incineration.

Composting at-home or through a service provider:

• Keeps food and yard waste out of landfills, which are the third largest source of anthropogenic methane emissions.
• Improves soil health, which supports higher crop yields without the need to use chemical fertilizers.
• Rebuilds topsoil, which increases the grounds ability to sequester carbon emissions from the atmosphere.
• Improves the structure of the soil which enhances water retention and means the ground is more resistant to drought.
• Aids in reforestation, wetland restoration, and habitat revitalization efforts by improving contaminated and compacted soil.
• Gets healthy soil into the hands of local famers and growers, which diversifies our food supply chains and ensures we have options when we eat.

For more details on the benefits of compost, check out the NRDC's Composting 101 article.

What is compostable?

There's often confusion around this, because the answer varies depending on the method used to compost!

If you're composting at home or a community garden, the following items are typically considered safe to compost:

• Fruits and vegetables
• Leaves
• Yard waste or grass trimmings
• Egg shells
• Coffee Grounds
• Tea Leaves
• Dead house plants (non-diseased)
• Non-glossy paper products like brown paper bags (best if shredded)

If you're composting with a service provider, or commercial compost facility you can often compost a wider range of material, including:

• The items listed above
• All food waste including meat, dairy, bones and oils
• Non-glossy paper, cardboard and paper towel rolls (including pizza boxes)
• Paper egg cartons (not made from styrofoam)
• Bamboo chopsticks and wood skewers
• 100% cotton (cut into small pieces or shredded)
BPI Certified compostable products like coffee cups and cutlery
BPI Certified compostable packaging
BPI Certified compostable plastics

It's important to note that your service provider or local facility may have additional rules about what they can and can't accept. These rules may be dictated by local regulations or in place to reduce contamination (like plastic), so it's important to familiarize yourself with the rules in your area.

Items that are not compostable:

• Plastic
• Metal and aluminium
• Styrofoam
• Produce stickers and packaging
• Items labeled "biodegradable"
• Take-out containers (unless they are specifically labeled BPI Certified compostable)
• Baby Diapers (there are no compostable baby diapers, and most facilities can not accept human waste)
• Fireplace and BBQ ashes
• Cigarettes and tobacco
• Drug or vitamin pills
• Dryer lint (most clothing is made with synthetic materials)
• Black walnuts (poisonous to other plants)
• Clam or oyster shells (basically rocks)

What are the different methods of composting?

These are the common methods of composting at home and at the bottom of this page are DIY resources for the common methods:

1. Aerated Turned Pile or Bin Composting (Common for Backyards)

The most common method for composting involves creating a small pile at a community garden or home backyard. The pile can be created directly on the ground, or in a bin. It's a particularly good method for breaking down yard trimmings and small amounts of food scraps. When properly created, maintained, and turned a backyard pile can produce compost in 3-5 months. If you're not turning your pile, you may notice smells or incorrect texture, and the pile may take more than 12 months to turn into compost. There is also a method for aerated static piles, which do not require turning, but do require more planning and set-up.

Meat, dairy, bones and large quantities of food scraps are not recommended for home and garden composting because the pile typically does not reach sufficient temperatures and can potentially attract pests if not managed properly.

2. Vermicomposting (Great for Apartments)

Vermicomposting relies on a species of worms, red wigglers, contained in bins to feed on food scraps, yard trimmings, and other organic matter to create compost. The worms break down this material into high quality compost called castings.

One pound of mature worms (approximately 800-1,000 worms) can eat up to half a pound of organic material per day! The worm bins can be sized to match the volume of food scraps that will be turned into castings, and it typically takes three to four months to produce usable castings.
The other byproduct of vermicomposting known as “worm tea” is used as a high-quality liquid fertilizer for houseplants or gardens.  Aerated (Turned)

3. Aerated Windrow Composting (Best for Larger Gardens and Farms)

Aerated, or turned windrow, composting is best for large volumes of food waste generated by entire communities or high volume food-processing businesses (e.g., restaurants, cafeterias, coffee shops). This is what you'll commonly see at industrial scale facilities or farms where thousands of pounds of organic material need to be turned into compost.

This type of composting involves forming organic waste into rows of long piles called “windrows,” and aerating them periodically by either manually or mechanically turning the piles. The ideal pile height is between four and eight feet with a width of 14 to 16 feet. This size pile is large enough to generate enough heat and maintain temperatures, but small enough to allow oxygen flow to the windrow's core.

Because of the temperature the piles can achieve (up to 160 degrees!), windrow composting can break down meat, fish, dairy, and bones as well as compostable products (cups, plates, utensils, etc. made from plants or plant-based plastics). The windrow method is what CompostNow uses at its commercial compost facility.

4. In-Vessel Composting (Varies in Scale)

This method involves feeding organic materials into a drum, silo, concrete-lined trench, or similar equipment which allows good control of the environmental conditions such as temperature, moisture, and airflow.

The material is then mechanically turned or mixed to make sure it's properly aerated. The size of the vessel can vary in size and capacity. While in-vessel composting can process the same variety of material as windrow composting, the equipment can be expensive and require technical expertise to operate.

This method can produce compost in just a few weeks, however it takes a few more weeks or months until it is ready to use because the microbial activity needs to balance and the pile needs to cool. Just like a fine wine, compost gets better as it matures.

5. Compost Service Provider (The Easiest Method)

If you don’t have the space, time, or resources to compost on your own, a compost service provider can be a great option for your household. The main benefit of a service provider is that they do all of the hard work for you and you can rest easy knowing your waste is being properly composted.

Compost service providers typically come at a cost depending on the area you live. Because the organic recycling industry is still new, compost is not subsidized like other waste streams such as landfilling and recycling, but at CompostNow, we believe it is critical infrastructure that should be invested in and developed.

6. Community Compost Programs (Most Accessible if Available)

These programs are typically developed by municipalities or public entities and are open to the community at little to no cost. While we would like to see a future where all communities are compostable in this way, there are a lot of operating and logistic barriers that prevent public entities from scaling this type of program.

A key challenge is the development of industrial compost facilities that can accept and properly manage large volumes of food and organic waste. The good news is that the demand for this type of infrastructure is increasing, and there are more federal, state, and local initiatives supporting the development of these operations.

Does compostable material break down in a landfill?

When compostable materials, like food scraps or compostable packaging, end up in a landfill, they do eventually break down over a long period of time. However, the decomposition process is much slower compared to a properly managed composting facility or home composting system.

In a landfill, organic materials like banana peels and carrots may take years or even decades to decompose fully in landfills, and during this time, they can release methane, a potent greenhouse gas, into the atmosphere.

What is a commercial compost facility and how is it different than my backyard?

A commercial compost facility, also known as an industrial composting facility, is a large-scale operation designed to process organic materials into compost on a larger and more efficient scale than what can be achieved in a backyard compost pile.

In addition to processing high volumes of organic waste, they typically have specialized equipment, and follow best practices for temperature control, feedstock and contamination control, compliance with regulatory agencies, and quality testing. Many use large aerated windrow piles to process the organic material, and are held to regulations dictated by local and state governing bodies.

Can I put my compostable plastic in my backyard compost pile?

Even certified compostable plastics are not recommended for backyard piles. This is because these materials require high temperatures at a certain duration in order to break down completely without leaving any residue.

Are paper coffee cups and other paper food containers compostable?

Unless they have the BPI Certified label, most paper food containers and packaging are not compostable. This is because the interior is often coated or reinforced with plastic to prevent grease and liquids from seeping through the paper.

How do I troubleshoot smells and issues with my compost pile?

Your compost pile should have a spongey, fine, and crumbly texture and be dark brown or black. It should have a mild earthy smell, like soil. Bad odor and slimy texture are signs that your compost pile is not decomposing correctly, and may need to be adjusted or turned.

According to the EPA:

• If your pile has a bad odor, it may be too wet or need more air circulation. Add more browns/dry material and turn the pile to introduce more oxygen.
• If your pile is not heating up, mix in more green material and turn the pile.
• If your pile is too dry, temperatures will drop. Maintain moisture levels of the pile by watering it if you have particularly dry weather.

A well maintained compost pile that has been turned regularly should take less than 5 months to be ready for use. If left unattended, the pile may take a year to decompose.

How do I use compost in my garden?

There’s a reason gardeners refer to it as “black gold!” Compost adds nutrients to soils, suppresses plant diseases and pests, and aids in water retention among many other benefits.

For raised garden beds, it's recommend mixing in compost with your choice of soil. The optimal mixture is ⅓ compost and ⅔ soil.

You can also use compost to dress the base of your plants (like trees, shrubs, potted plants, etc) and amend your lawn. For this use, it's recommended adding 2 inches of compost on the surface. To calculate how much compost you need, use this calculator.

Need more inspiration as to how to use compost? Check out these helpful resources:
• Earth Matters: How to use compost
• US Composting Council: Methods for using compost

Are electric counter-top machines the same as composting?

There are no electric counter-top containers on the market today that create compost. In fact, many have come under scrutiny for calling the output of the machines compost, fertilizer, or soil, and have had to reduce to calling it "dirt-like material." These machines primarily dehydrate and grind the material, but the output cannot be called compost or even soil. BioCycle explains the confusion commonly caused by these devices, and explains what is not compost!

This article outlines the other issues with current electric counter-top devices.

Ready to compost?

Below is a compilation of all the best resources for beginner and intermediate composting you can find on the internet. We did the hard work, so you don't have to search through un-helpful links.

Want to compost in your backyard or apartment?

There's so many great resources for starting your own compost pile! If you're into worms, there's even options for composting in apartments.

Below are our favorite links and resources for do-it-yourself composting:

How to start composting in your backyard (
Choosing the best DIY compost method infographic (Gardens That Matter)
13 compost bin designs with build instructions and materials (CalRecycle)
No backyard? Vermicompost could be the answer (
Beware: electric counter-top devices do not create compost (Gear Patrol)

Don’t have the time, space, or resources to compost on your own?

Compost pick-up and drop-off services are a great way to reduce your household waste. This map shows compost services you can see if service providers exist in your area! Depending on where you live, there may even be compost services for businesses!

Composting has only recently been prioritized and funded by the federal government. If you're not seeing options near you, check out this article and start a conversation with your community representatives.

Still have questions? Let us know!

If this page didn’t answer your questions about compost, email us at