Hot composting is a fast way of creating large quantities of high quality compost. To do it successfully, close attention must be paid to maintaining a 25-30:1 carbon to nitrogen (brown stuff to green stuff) ratio, moisture content and aeration. This is style of composting gets lots of attention, probably because it is employed by large scale backyard growers and other intensive gardeners to such a successful degree. A closely managed hot pile can create finished compost in as little as a month under ideal conditions.
Starting a hot compost pile is rather simple. Begin by spreading a four to six inch layer of brown material like straw, leaves or dried stems over an area of at least three feet long and three feet wide. Next, add a two to three inch layer of green material such as grass clippings, weeds and kitchen vegetable scraps. Then spread a few shovels full of soil over the top and wet the pile thoroughly. Continue adding layers in this manner until the pile is at least three feet high. Turn the pile every couple of weeks, working the outer stuff toward the center of the pile and the inner stuff outward, and adding water if the pile seems to be drying out. A hot compost pile may reach 140 degrees Fahrenheit, at which temperature most weed seeds and plant diseases die, making this a convenient way to dispose of all but the most worrisome of garden debris.
Cold composting is a good way for small scale gardeners, or those without the time or energy to closely monitor a hot pile, to make compost. An important benefit of this style of composting is that it works on an “add as you go” basis, meaning that kitchen scraps and garden debris may be piled on at any time. Also, no turning is required. Cold composting generally takes a year or more to turn raw material into finished compost.
You can make a cold compost pile by simply piling up garden and kitchen debris as it becomes available, and waiting anywhere from several months to two years for the stuff to break down. If you keep adding to the pile through this waiting period, simply scrape the fresh material off the top and pull the finished stuff off the bottom when you need it. Because the work of decomposition in a cold pile does not generate heat, it does not kill weed seeds or plant diseases, so it is important to be cautious what goes into the cold compost pile. It is not recommended to add noxious weeds that have gone to seed or diseased plants.
Compost tumblers are simply designed to work as an enclosed hot pile, and they do have the ability to make finished compost in a matter of a few weeks. In reality, however, tumblers are often used as a hybrid style of composting, making small batches of compost on an add as you go basis in a matter of a few months. The benefit of using a tumbler is that it is clean and convenient, requiring only an occasional push to turn the bin and a little water now and then.
Compost tumblers were invented to make the work of turning the pile easier. They are generally some variation of a barrel attached to a metal rack, allowing it to be spun in place, with a door on the side to add material or empty finished compost. For it to work optimally, there are a few things to know. First, the carbon to nitrogen (brown to green) ratio is very important for quick breakdown. Keep it as close as possible to 25:1. Secondly, a new compost tumbler is sterile and there will be no help from soil contact so it must be inoculated with compost starter for the first batch or so. Grinding the material into small pieces will help the microbes to break it down more quickly. Finally, keep it wet...like a wrung-out sponge. Also, if you want you compost in nice, neat batches all at once, load the tumbler in nice, full batches all at once.
Worm composting is absolutely fascinating. Red wiggler worms are the species of choice, and they can devour an amazing quantity of kitchen scraps and cellulose in a short amount of time. This is a great option for apartment gardeners or those with limited space. It’s also a very visual and tactile way to teach kids about composting.
Start a worm composting bin by drilling air vent holes in the sides and top, and water drain holes in the bottom of a plastic storage bin. Fill the bin three quarters full with moistened shredded cardboard and newspaper and a few handfuls of garden soil for bedding. Let the bin stand for a day, then add the worms. Feed the worms every few days with shredded kitchen scraps, including vegetables, crushed eggshells, stale bread, coffee grounds and tea bags. Bury the scraps several inches into the bedding. The food will take a week or two to disappear, so bury successive feedings in different locations each time. Replenish bedding as needed. Worm compost will be ready to harvest in two or three months.
Using Your Compost
Compost is a useful soil amendment, but there are a number of other ways it can benefit your plants. Using it as mulch is like side-dressing with a slow release fertilizer; it helps keep plants looking great and growing strong. Steeping a mesh bag of compost in a few gallons of water for a day or so makes compost tea, a fantastic foliar tonic that feeds and protects plants. Amazingly, you will find that you can never make enough fantastic compost.