Composting Methods & Bins
Find out about composting yard waste and food scraps using a variety of methods.
Yard Waste Composting
Composting lawn clippings, leaves and other yard waste can be done in a 3 x 3 x 3 open pile or in a variety of different bins. Open piles may need to be covered with plastic to prevent them from becoming too dry or too water saturated. They also need to be mixed as the inner part of the pile becomes composted. A compost bin will allow you to compost on a smaller scale. Material will decompose more quickly and at a higher temperature if the bin has a turning system.
Compost can be created from equal parts of brown materials that are carbon rich (such as leaves, dead flowers, corn stalks, and shredded newspaper) and green materials that are nitrogen rich (such as grass clippings and annual flowers). Weeds are not recommended for backyard composting as the material in most piles and bins does not get hot enough to kill all weed seeds. The contents of the pile or bin should be kept as wet as a wrung-out sponge. Too much green material can make the contents too soggy whereas too much brown material can make the contents too dry. There are separate composting systems for food waste, since including food waste in your yard waste will likely attract rodents.
Food Waste Composting
Food waste should be composted in a worm bin, food digester, Green Cone, or buried directly in the yard. It should not be composted in an open pile with yard waste to avoid attracting disease-carrying pests such as rodents.
Food scraps can be kept inside the house in a plastic container, bucket with a lid, or the freezer for a few days before they are taken to the compost bin or yard. If smells or flies become a problem it can be helpful to sprinkle an inch or two of sawdust, peat, or coconut coir over the top of the food in the container.
Greens, such as fruits and vegetables, breads and grains, coffee grounds and tea bags can be composted. Meat, poultry, fish and dairy can be placed in yard waste bins to be picked up by your local solid waste utility. Placing them in a paper sack or other approved biodegradable bags before adding them to your yard waste bin will keep things tidy. Pet wastes should not be composted but instead placed in the garbage.
Worm bins can be purchased or made from wood or plastic. They should be at least one foot deep, have a tight fitting lid and have holes drilled in the bottom for drainage. A four foot long by two foot wide by one foot deep worm bin will compost about 8 pounds of food scraps a week. Bins can be placed in a basement or enclosed garage or outside in a sheltered location. Worms can be killed by hot dry weather in summer or cold temperatures in winter. Composting will also slow down in cooler temperatures.
The worm bin should be filled with bedding such as leaves, shredded cardboard or newspaper, straw, or untreated sawdust. The materials should be soaked in water so that the bedding is as moist as a wrung-out sponge before adding to the bin. About one pound of red worms can then be added to the bin. Food scraps can be buried in the bedding so that there is at least one to two inches of bedding over the top. Each week, food scraps should be buried in a new spot. A sheet of plastic or newspaper over the top of the bedding will keep flies to a minimum.
After six to twelve months most of the bedding will be composted. This dark rich material can be pushed to one side of the bin while new bedding is placed on the other side. Bury food scraps in the new bedding only until all of the worms have migrated to it, and the old bedding is completely composted. Then compost can be removed from the bin and new bedding added to this side.
Green Cones and Food Digesters
A food digester is a partially buried metal garbage can or plastic container with a tight fitting lid that has holes in the bottom. A green cone has a bottom basket that is buried in the ground and a screwed on top cone with a lid for adding food scraps. Food scraps are placed in the food digester or green cone until it is filled and then left to complete composting for 6-12 months. It is preferable to have two food digesters or green cones so that one can be in actively use while the other is composting.
Burying Food Directly in the Yard
To bury food waste directly in the yard, start by digging a hole about a foot deep, adding two to three inches of chopped up food scraps, and covering with at least 8 inches of soil. When burying food directly in the yard, check periodically for signs of digging by dogs or other pests and if a problem develops switch to another composting method.
Master Composter/Soil Builder notebook available for review in Seattle Tilth office.