How to Build a Hot Compost Pile
7 of 7 in Series: The Essentials of Composting
If you want compost in a hurry, a hot pile suits your style. They heat up to temperatures of 120 to 170 degrees Fahrenheit (49 to 77 degrees Celsius) within 1 to 5 days, with 150 degrees Fahrenheit (66 degrees Celsius) being a typical peak. Your role is to help the pile maintain high temperatures by monitoring it with a thermometer and turning all the material when the temperature cools. Also, you want to make sure the pile doesn't get too hot (staying above 150 degrees for more than a few hours) because that much heat will kill beneficial microorganisms that add value to your composting process.
A well-constructed and properly managed hot pile will turn organic matter into compost within four weeks.
To get started on your quick-decomposing piles, gather these materials:
Equal parts green and brown materials, all shredded to a small size. Fresh grass clippings and dried shredded leaves work great for your first effort because they're already in small pieces, and the grass clippings are full of moisture.
A fork and/or shovel for turning
A compost thermometer or a meat thermometer attached to the end of a stick
A tarp (optional)
A bin (optional)
When you have everything you need to get started, follow these steps:
Chop or shred organic matter into small pieces.
Toss the greens and browns together in a well-blended mix (not layers).
Add a shovelful of already finished compost or native soil, which will be full of microorganisms to jumpstart the process.
Sprinkle water as you build, moistening all the organic matter to the consistency of a wrung-out sponge.
Your final pile must be at least 3 cubic feet (1 cubic meter) in size and no more than 5 cubic feet (1.5 cubic meters) to help maintain sufficient heat and moisture to speed decomposition.
Optional: Cover with a burlap or other breathable tarp to maintain moisture.
Monitor and record your pile's daily temperature with a compost thermometer.
Temperatures will rise to 120 to 170 degrees Fahrenheit (49 to 77 degrees Celsius), usually within one to five days.
Temperature trends are approximate and vary depending on the type of materials you're composting, the size of the pieces, the level of moisture, and so on. Monitor the trend of rising and dropping temperatures, but don't worry about achieving exact readings.
Every four to seven days, when the temperature of the pile cools below 110 degrees Fahrenheit (43 degrees Celsius), turn all of the organic matter to introduce more oxygen and heat it back up.
Thoroughly mix materials from the pile's exterior to the interior. If needed, water as you turn to maintain the wrung-out-sponge moisture level. Be careful not to get material too wet, because doing so cools off the pile.
After about 14 days, the ingredients of the organic matter will no longer be recognizable. Continue monitoring and recording daily temperatures and repeating the turning process.
Turn every four to five days, when the temperature drops below 110 degrees Fahrenheit (43 degrees Celsius). Remoisten if needed. Turn a total of four times throughout one month.
After 1 month, the pile no longer heats up after turning, and the bulk of it is dark, crumbly compost.
The temperature drops to 85 degrees Fahrenheit (29 degrees Celsius) or lower.
At this point, let the compost "cure" for one to two weeks before spreading around plants or adding to gardens for planting.