Large Compost Bins
What are large compost bins?
Bins are a tidy way to compost outdoors. They keep materials compact and help maintain the damp, warm conditions needed for decomposition. Large compost bins are over 36 ft3 in capacity. Some commercial wooden bins and some homemade bins fall within this range.
- Start by siting the bin on top of grass or soil. Ideally it should be in partial shade, but bins can also go in full sun or full shade if necessary. Try to put the bin somewhere that it is convenient to use.
- Optional: Take a length of PVC plastic pipe about an inch shorter than the top of your bin and drill small holes down it on at least two sides. Place this vertically into the bin and add your materials around it. This pipe will let air get into the compost as it breaks down. If you are using a large bin with multiple stalls, you can place a pipe in each one.
- Add green material* (kitchen waste, green plants, or grass clippings) as it is available from your home and yard.
- Balance each addition of green material* with a slightly larger amount of brown material** (dead leaves, dead plants, woodchips, or shredded paper products) at the same time. It is useful to keep two or three bags of dead leaves around for this purpose throughout the year.
- Add a small scoop of soil or finished compost after adding greens and browns.
- Add enough water to dampen the compost all the way through.
- To maintain: Keep the compost damp by adding water when necessary. Stir the compost with a compost aerator or poke holes into it with a piece of rebar every week or so to keep air pockets open.
- If you are using a large bin with multiple stalls, switch from one stall to another when the first is 4/5 full. Start building a new compost pile in the next stall while the first finishes processing. Remember to still keep all of the stalls damp during this time.
Depending on particle size and specific materials used, some compost should be finished after 3-6 months. Finished compost is dark brown and crumbly, and has a damp earth smell rather than a sour smell. It may still have bits of unprocessed brown material present; this can either be ignored or sieved out with wire mesh. Finished compost can be dug into soil, used as a top-dressing, raked onto a lawn, or used in a potting mix blend.
What composting style do they fit?
Large compost bins work well for both hands-off and hands-on composters. The bins have enough capacity to deal with large volumes of yard and garden waste, even if they are not kept processing quickly.
Hands-on composters should only choose a large bin if they have large volumes of yard and garden waste.
What space does it need?
Large compost bins need an outdoor space on grass or soil. They work best in partial shade but can be placed in full shade or full sun if necessary.
How do they work?
Large compost bins are a form of aerated composting which relies on naturally-present decomposition microbes to digest organic waste and turn it into finished compost. These microbes require 5 things to function properly:
- Green material* (this should be about 40% of the mix)
- Brown material** (this should be about 60% of the mix)
- Oxygen (air)
- A small amount of soil or finished compost
*Green materials are nitrogen-rich, fresh stuff such as green plants, grass clippings, and kitchen waste. Kitchen waste here includes vegetables and fruits, tea bags, coffee grounds and filters, egg shells, and grain-based products but excludes meat, bones, dairy, and grease.
**Brown materials are carbon-rich, weathered stuff such as dead leaves, dead plants, sticks, woodchips, and shredded paper products.
If the compost doesn't seem to be breaking down, check that it is still damp all the way through. Add water if necessary. If it is damp and still not breaking down, consider adding additional green materials* to the mix.
If the compost has a putrid smell, fluff it to add air and stir in additional brown materials.** Small amounts of soil can also be added.
Can you use it all year?
A large compost bin can be used all year. While decomposition will stop in winter, organic waste can still be added as long as there is room for it. Consider harvesting any finished compost from the bin in fall to make extra room. You may also want to site the bin close to your back door or next to a cleared pathway to make taking kitchen waste out more convenient in snow.
Large bins are unlikely to run out of room, but if they do, you can place kitchen waste into paper bags or sheets of newspaper and store frozen outside until spring, when the contents of the bin should shrink and make more space. Alternatively you may consider adopting an indoor composting method during the winter such as bokashi buckets, vermicomposting, compost tubs, or a NatureMill electric composter.
Testing them out:
Got more composting questions? Email the Composting Hotline at [email protected] or leave a message at (306) 931-3249. We will get back to you within 1 business day.
Residents of Saskatoon can also use the hotline to request a free home visit from a Compost Coach. Our Coaches can provide composting advice, help you set up a new compost system, or troubleshoot and existing system. Visits typically take 15-45 minutes.