Looking for an easy, hands off way to compost? Trash bag composting may be a good option! It’s also one of the best ways to compost during the winter, when outdoor bins are dormant due to cold temperatures.
To make compost in a garbage bag, you’ll primarily use yard waste or other brown, carbon rich materials. Autumn is a great time to start the process of trash bag composting due to the abundance of dried grass, brush, and fallen leaves.
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What is Trash Bag Composting?
First of all, let’s talk about compost. Compost is simply organic material that has been broken down over time by microbes (bacteria and fungi). Finished compost looks like crumbly, black dirt, and it’s used to fertilize soil to grow healthy plants.
There are many different ways to create compost. No matter which method you choose, minimizing food and other waste to make compost is good for the environment.
Trash bag composting is exactly what it sounds like. Compost is created inside a garbage bag, primarily with yard waste. The process takes about six months to a year, which is typical of many composting methods. Therefore, compost started in the fall could be ready to use in spring gardens!
Composting can be done anaerobically (without oxygen) or aerobically (with oxygen). We’ll mainly focus on the anaerobic version in this post, which is the simplest method for composting in garbage bags.
Trash Bag Composting: Pros and Cons
Not sure if this composting method is best for you? Consider these pros and cons before deciding to compost in a trash bag.
Pros
- low cost or even free: Sturdy black trash bags are the only expense here, and there’s a good chance you may already have some of those laying around.
- no maintenance: There’s absolutely no maintenance for composting anaerobically in a garbage bag. You literally set it and forget it for up to a year. No turning required!
- perfect for small spaces: No space? No problem! You can choose the size of the bag for composting and store accordingly.
Cons
- may take a long time: This composting method is often started in fall when there are plenty of fallen leaves and dead grass. That means the composting part happens throughout the winter, with little heat so it needs extra time.
- plastic bag usage: If you’re aiming to lessen your reliance on plastic bags, you may want a more permanent composting bin. Otherwise, the garbage bags can be reused.
- methane gas: Composting without oxygen will create a small amount of methane gas, which is a known culprit for raising the ozone’s temperature. It’s still a tiny amount compared to what a landfill produces, and you get usable compost.
How to Make Compost in a Garbage Bag (Anaerobic Version)
Here’s what you need to get started with trash bag compost, plus step by step directions for success.
Materials Needed for Trash Bag Composting
The materials needed to start composting via the garbage bag method are below:
- 2 black trash bags
- Brown, carbon rich materials
- Soil or finished compost
- Green, nitrogen rich materials (optional)
- Water
- Heat
Black Trash Bags
Heavy duty black trash bags are preferred for both their durability and ability to trap heat inside, even with colder temps outdoors. Black material naturally absorbs heat. That’s key for composting in the dead of winter with little sunlight.
Composting experts recommend double bagging the materials just in case the first bag gets punctured by a twig or other sharp object. It also prevents any oxygen flow.
PRO TIP: You can find contractor style, black garbage bags at most retail stores. Or better yet, ask around and acquire a couple from a friend or Buy Nothing Group.
Brown, Carbon Rich Material
The brown materials provide microbes with carbon, which is necessary for decomposition.
Dried leaves, hay, or dried grass clippings work best for this composting method.
No yard or trees to collect brown material? Ask a friend or neighbor for their yard waste.
You can also add shredded paper, cardboard, dryer lint, or wood chips as brown material. Shred the brown material into smaller bits to speed up breakdown. Just remember you won’t be re-opening the bags once they’re tied off, so add in all waste upfront.
PRO TIP: Avoid black walnut tree and eucalyptus leaves as brown material for compost. These plants contain natural herbicides that are harmful to seeds and gardens. Also- never plant a garden near a black walnut tree!
Soil
Soil (or finished compost) will help kickstart the decomposition process by introducing plenty of microbes.
The weight of the soil also ensures the trash bag stays in place. Otherwise, a bag full of leaves and grass clippings could easily be blown around. Consider adding a heavy rock or two for extra poundage as well.
Green, Nitrogen Rich Material
Adding green material to trash bag compost is optional, but it will help speed up the process.
Greens provide the essential proteins for the microorganisms breaking down the organic matter. This nitrogen is also an important component of chlorophyll, which is key for plant photosynthesis (the conversion of light energy to produce sugars from water and carbon dioxide).
Water
Water is important for every method of composting. Microbes in compost need water just like any other living organism. It helps the decomposition process and regulates temperature.
Add a quart or two of water to the materials in the trash bag and mix well. The contents should be moist, but not drenched. Grab a handful of the organic material and give it a squeeze. If water seeps out, there’s too much. Instead, it should feel like a moist, wrung out sponge.
Heat
Ideal temperatures for composting are between 90 to 130 degrees F (32-54 degrees C). Heat speeds up the process and can kill weeds, disease pathogens, and harmful insects.
Will compost in a garbage bag ever reach these temperatures in the dead of winter? Probably not. Otherwise, the plastic bag would melt. However, the black trash bag traps in heat and raises temps enough to decompose the materials, just at a much slower pace.
Step by Step Directions for Trash Bag Composting
Producing compost in a trash bag without oxygen is actually very easy. It involves four key steps:
- Place all materials (see below) in a heavy duty, black trash bag and mix well. Fill the bag to capacity for best results.
- browns: 2-3 parts
- soil or finished compost: 1 part
- green materials, if using: 1 part
- water: 1-2 quarts
- Squeeze any air out of the trash bag and tie it so there is zero air flow inside.
- Then place the bag inside a second black trash bag and seal again. This is double protection against any rips or tears that may occur.
- Finally, store in a sunny location away from pests or in a heated location indoors and wait patiently for at least six months to 1 year.
Some suggest compost may be finished in as little as 6 to 8 weeks with this method, but it’s best to wait longer to ensure all material is broken down.
Results may vary depending on materials used, where it’s stored, temperature, and how long the mixture sits.
Trash Bag Compost Troubleshooting
Use these tips and tricks for a successful garbage bag composting experience.
Are Black Trash Bags Necessary?
Black, contractor trash bags are preferred because they trap in heat well, but any sturdy garbage bag will work.
Use whatever size works best for your space.
Can I use biodegradable or compostable trash bags to make compost?
Most eco friendly trash bags are made of very thin plant-based material. Although they’re better for the environment overall, they aren’t structurally sound for making compost.
Will the Garbage Bag of Compost Become Smelly?
You won’t be able to smell compost in a sealed off container, although it may smell acidic if opened too soon. The finished product will smell Earthy, or like fresh soil.
How to Keep Pests and Rodents Away from Compost
Pests or insect can become an issue if food scraps are added to the material. They can chew thru the bag, disrupt the composting process, and leave a huge mess.
Spray a water and vinegar solution on the trash bag exterior and on the ground around the bag if storing outdoors.
Some animals are deterred by citrusy smells as well. Spritz an orange peel and vinegar mix on the bag for even more protection.
How to Tell When the Trash Bag Composting Process is Finished?
Don’t prematurely open up the trash bag until the microbes have had time to do their job. Feel around the outside of the trash bag and check for any clumps or large pieces of debri. If you can feel individual items poking about, the compost isn’t finished.
Give the bag a squeeze as well. Compost will feel like crumbly dirt when it’s ready.
Cooler temperatures will cause the microbes to work slowly, so allow compost to sit for at least six months at a minimum.
Is Aerobic Composting Possible in a Trash Bag?
Aerobic trash bag composting is possible, but it requires much more effort. Poke small holes in the trash bag to allow oxygen flow, but not large enough for contents to spill out.
Compost made aerobically (with oxygen) needs to be turned and mixed frequently, about every other day. Rolling a garbage bag full of yard debris on the ground may easily cause ripping or damage. For best results, place the trash bag of compost in a large bucket or barrel and then tumble it around.
Looking for more ways to compost? Here are 16 different ways to compost at home, no matter your budget or space!
Looking for more ways to create less waste around the home? Grab the 30 Days to Waste Less calendar. Click ‘get the guide’ to download the PDF now!
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