Written by volunteer Stephanie de Moll
A single slice of moldy bread, a rotten tomato, an apple that’s been in the fridge too long—it happens to everyone at least once. Instead of tossing that kitchen waste into the trash, gardeners can make good use of it. Sometimes called black gold, compost is a nutrient-rich fertilizer and soil additive easily made at home. It adds drainage to clay and heavy soil and increases water retention in loose or sandy soil. When used as mulch, compost inhibits weed growth and protects soil from drying out. Compost can turn a good garden into a great garden.
To start, get a bin. Tumblers are perfect for small batches and create compost quickly, usually in a few weeks. Stationary bins can be as simple as a wire cage set on the ground. Stationary bins can also be elaborate, multi-sectioned boxes. The Oregon Garden’s Home Composter Demonstration Center is an excellent reference for compost containers and how-to info. The Center features several types of bins, so gardeners can find the right container for any garden or household. Even a garbage can with holes drilled in it works very well.
The best place to set the bin is a sunny or partly shaded location. Bins should be placed on soil to encourage the growth of beneficial microbes. Tumblers can sit on concrete. Whatever the container, it should be easy to fill and to keep the contents turned.
Filling your Bin
Once in place it should be filled with three types of ingredients: start with brown matter such as twigs, wood chips, or straw; add green plant matter such as grass clippings, plant trimmings, manure, and kitchen scraps; water–keep it moist but not soaking wet. By starting the first layer with chunky, dry materials the pile will maintain good airflow. Additional brown matter can include dry leaves and shredded paper, such as junk mail. A layer of garden soil helps introduce micro-organisms that will start the composting cycle. Then continue layering the brown and green materials. Add enough water to keep everything slightly damp throughout.
Large items such as cornstalks and twigs should be chopped or shredded. Corn cobs are a great addition but take a long time to decompose. Newspaper and cardboard should be soaked before adding to the container.
Maintaining your Compost
Commercially available activators can jump start a new bin or reheat slowed compost. The activator is added among the layers and helps speed up the decomposition process. Though not necessary, such a product can shorten the time waiting for the ingredients to turn into compost. Or start with a good amount of lawn clippings, which make a great activator.
In general, a bin of debris can take one to two years to turn into usable compost. The amount of time varies depending upon several factors including the amount of heat the bin generates, how often the compost is turned, and whether or not the bin is kept moist. Proper care of the bin ramps up decomposition.
Regularly add new material, especially green. Mix the new waste into the compost rather layering it on top. The bacteria need fresh food to consume. Mixing also helps keep the compost warm and cooking. The pile requires regular turning, usually once every week or two. Use a pitchfork, garden fork, or compost aerator to blend the materials. Keep it slightly damp at all times. The moisture level should be checked during hot, dry weather. Dry mix will decompose but very slowly. And a pile that’s too wet will only turn into slime.
A properly maintained bin won’t smell. Gardeners concerned about attracting pests can bury kitchen waste beneath lawn clippings or other matter. Keeping the compost turned should help discourage interest from wildlife. Turning also adds air to the mix, vital for decomposition. Rotating bins make this job easier, but they limit the amount of compost a gardener can make at one time.
Those who don’t have a tumbler and are looking for a more convenient system may be interested in no-turn composting. This simple method is an excellent way to interest children in composting as it requires less work. Begin the pile with plenty of coarse, loose material such as wood chips or small twigs. Mix this bottom layer well with green matter. After that, continue adding new waste materials to the top of the pile without further mixing. It’s a good idea to keep the pile covered with black plastic in order to generate heat since the waste will take much longer to break down than if it is turned regularly.
Once the process has finished, harvest the compost from the bottom. The best type of bin for this method has a reservoir in the base to hold the finished compost. A multi-sectioned bin is another good choice, and The Home Composter Demonstration Center has one on display.
Home composting is easy, and some techniques are easier than others. There are many commercial bins available, or gardeners can make one with little effort. No matter the approach, composting is one of the best things gardeners can do for the environment and for their gardens.
What to Compost
Some materials are great for composting, some aren’t, and there are some things that should never be added to a compost pile. While most plant material is excellent as either green or brown matter, diseased plants and weed seeds are two items that are better off in the trash.
Stuff that should not be composted
- Meat, fish, bones, and dairy foods
- Inorganic materials such as plastics and pressure-treated lumber (contains chemicals)
- Synthetic chemicals including pesticides and herbicides or plants that have been treated with synthetic chemicals
- Pet waste
- Colored paper including newsprint
- Charcoal or coal ash
- Anything from black walnut trees
Green and brown materials that can and should be composted
- Shredded twigs
- Peat moss
- Pine needles
- Vegetable stalks and peels
- Fruit and fruit peels
- Pond algae
- Coffee grounds
- Paper tea bags and tea leaves
- Plant trimmings
- Dead flowers
- Lawn clippings
- Wood ash
- Blood meal (as an activator)