Active microorganisms need a moist environment. Ideally, composting materials should be between 40 and 60 percent water. When conditions are too wet, water will fill the pore space needed for air movement, and anaerobic conditions can result. If conditions are too dry, the decomposition rate will slow down.
If your compost bin is too dry it will stop decomposing as the bacteria and fungi responsible for the composting process won't be able to work effectively. Re-wet the heap by watering it - ideally with rainwater, but if you don't have any stored rainwater ordinary water will do.
Too much water can smother the pile, which means your organic waste won't decompose and you'll get a slimy and smelly pile that could well answer to the name “swamp thing.” Too little water and you'll kill the bacteria and you won't get your compost (see Managing Moisture in Compost).
Most expert composters suggest a moisture content of 40% to 60%. A quick, hands-on visual check should tell you if the pile is too dry: it will lack heat and there'll be little evidence of organic material break down. If you compost is too wet, it's probably slimy and smells bad.
As a rule of thumb, actively decomposing materials should be turned every three to four days. Materials with slowed microbial activity can be turned less often. In tumblers, turning two times a week resulted in higher temperature and faster decomposition than turning once a week or once every other week (Figure 1).
Composting works in sun or shade Piles in sunny spots will decompose quicker but also dry out faster and may need supplemental watering during hot dry weather. Those located in a shadier spot will stay moist longer but decompose slower.
Compost is ready or finished when it looks, feels and smells like rich, dark earth rather than rotting vegetables. In other words, it should be dark brown, crumbly and smell like earth. The Florida Online Composting Center is one of the few sites that offers detailed home tests for the maturity of compost.
After the pile reaches around 80-90 degrees Fahrenheit, you want to stop adding greens and limit the amount of browns so that the compost can cure. Keep turning the piles regularly to add oxygen.
You can put your compost pile in the sun or in the shade, but putting it in the sun will hasten the composting process. Sun helps increase the temperature, so the bacteria and fungi work faster. This also means that your pile will dry out faster, especially in warm southern climates.
Test whether the compost is ready...
Decomposition will be complete anywhere from two weeks to two years depending on the materials used, the size of the pile, and how often it is turned. Compost is ready when it has cooled, turned a rich brown color, and has decomposed into small soil-like particles.
Simple organic activators you may have on hand are lime (limestone), blood meal (yes, it's dried blood), fish meal, and poultry, rabbit, and horse manure. Rabbit food (pellets) and dry dog food are also organic activators that are often have on-hand.
Fertilizer can be helpful in your compost when added in limited quantities. Fertilizer and minerals in the compost pile support bacteria while also improving compost quality — thanks to increased amounts of nitrogen, phosphorus, and potassium.
If a compost pile is just left sitting, and not turned, it will take 6-12 months or longer to completely break down, depending of the climate and weather. The cooler it is, the longer it will take.
It will lose much of its value if materials are left to decompose too long. The more time compost is left to sit around, the more “colloidal” it becomes. In other words, it becomes more and more compact as the composting microbes continue to feed on the waste materials.
Adding too much compost may be harmful, especially in vegetable gardens. You can apply too much compost at one time or over several years. Too much compost in soil stunts plant growth. It also may create water pollution.
Vinegar is a natural weed controller because of its acidic nature. It also deters pests and can work wonders in your garden. Apple cider vinegar also contains many valuable nutrients that can benefit the compost pile. Pickles can also generate vinegar, which is also compostable.
One that might surprise you, lettuce takes 25 years to decompose! So it's important to not throw food on the side of the road or in nature, as it takes food a whole lot longer than you might think to biodegrade!
Turn your compost
Some systems recommend turning your compost heap every day or two (see the Berkeley method below), but even turning it once or twice will help speed up the composting process. If you do decide to turn it regularly, considering getting a compost fork to help make the process easier.
Composting becomes even easier without compost bins. Burying the compost directly in the garden bed reduces time and energy spent. Vegetable plants still get the same benefits of traditional composting methods.
A compost-bin lid should actually not be airtight — you want scraps to begin decomposing aerobically (with oxygen), not anaerobically, which makes organic matter take longer to break down and releases smelly gasses, like methane.
Home gardeners are encouraged to wear a face mask and gloves while handling potting mix and compost, and to wash their hands thoroughly, to avoid contracting Legionnaires' disease.