To turn the trees’ bounty of autumn leaves into rich, useful compost for your garden, you’re probably going to need a bin.
“A compost bin is neater than an open pile and generally more efficient, especially in the winter,” said Sharon Yiesla, plant knowledge specialist in the Plant Clinic at The Morton Arboretum in Lisle.
At the same time, a bin needs to admit air and water for the bacteria, fungi, insects, arthropods and other composting organisms that will break down your leaves and other plant materials.
Effective composting requires a large enough quantity of materials to support the composting organisms. A substantial mass will also retain enough warmth to help continue the breakdown process during cold weather.
“The rule of thumb is 1 cubic yard, or 3 feet by 3 feet by 3 feet,” Yiesla said. That volume is a little more than 200 gallons.
Some municipalities, including Chicago, require enclosed bins with lids to deter animals. Check with your local officials about home composting regulations.
You can buy or make a compost bin, but first, think through how you will use it. Do you want to access finished compost little by little, or wait to harvest one big batch? “It also makes a difference whether you will include kitchen scraps in your compost or just yard waste such as fallen leaves,” Yiesla said. Yard waste alone is less attractive to animals and requires less fortification.
The style of bin you choose will depend partly on where you put it. Make sure you will have space to get at the door or other opening. Consider too where you can place your compost to be respectful of your neighbors. Different compost bin styles will work for gardeners in different situations.
Here are some common types to consider:
Open bin: Made of wood, wire mesh or perforated plastic, an open bin, often called a batch composter, is the simplest style. It may be square or cylindrical. You pile in plant materials, wait until they all break down, and harvest the whole batch at one time. Often an entire side can be removed from the bin to harvest finished compost. For a steady supply, some gardeners have three bins — one that’s being filled up, one that’s breaking down and one with compost that’s ready to use. “Open bins are easy to build and inexpensive to buy,” Yiesla said. They also make it easy to turn the compost, mixing in air to speed up the process. But they do not deter animals.
Through-and-through bin: This is an enclosure, usually roughly a cube or cylinder, with a lid on top that can be opened to add material and a door near the bottom for harvesting compost. Plant material gradually breaks down as it is buried and moves down the column. Finished compost is available most of the time in this type of composter, but only in small quantities. Since the materials are not mixed or turned to bring more oxygen to the organisms, compost forms more slowly. Air circulation through openings is especially important in these bins. Although they are more expensive, they are relatively animal resistant.
Tumbling composter: This is essentially a plastic can with air holes, which you fill with plant materials and agitate either by rolling it along the ground or by turning it around an axle with a hand crank. The selling point of compost tumblers is speed: The frequent turning supplies plenty of oxygen to the organisms so they can break down materials fairly quickly, often in a few weeks. However, the quantities are small and the compost is available only in batches. “You also have to do the work,” Yiesla said. “They don’t tumble themselves.”
To learn more about how to make and use compost, see mortonarb.org/composting.
For tree and plant advice, contact the Plant Clinic at The Morton Arboretum (630-719-2424, mortonarb.org/plant-clinic, or [email protected]). Beth Botts is a staff writer at the Arboretum.