According to the USDA's Natural Resources Conservation Service, hot compost can attain temperatures up to 160 degrees F. Rather than waste this naturally produced result of the vigorous microbial activity in your wood chip compost, use it as a budget-friendly method to heat your greenhouse. Although a wood chip compost heap certainly won't produce enough warmth to heat your home, it typically provides enough heat to keep a small, one-family greenhouse within the proper temperature ranges necessary for starting plants during the early spring season.
Section off a 4-foot-by-4-foot area of your greenhouse, marking the corners with wooden stakes hammered into the ground. If possible, opt for your wood chip compost heap to be on the side of your greenhouse that gets the most wind to help insulate your plants from the effects of the cold air on that side of the building.
Collect equal amounts of carbon-rich wood chips and nitrogen-rich cow or horse manure. Sift through your collection of wood chips, chopping larger pieces into smaller sections that measure less than about 2 inches in diameter to minimize the amount of work the decomposing microorganisms will have to do to break down the wood waste.
Spread a 2- to 3-inch layer of wood chips across your marked-off greenhouse compost pile location. Place a 2- to 3-inch layer of your high-nitrogen animal manure on top of the wood chip layer. Toss two shovels of plain topsoil atop the animal manure layer to provide an organic compost activator, which kick-starts the microbial activity in your pile to produce heat more quickly.
Moisten the layers of waste with a trickle of water from your garden hose, wetting the organic material until it is about as damp as a wrung-out sponge. Spread additional layers of organic waste, alternating the wood chips with the animal manure layers until your compost pile measures minimally 3 feet tall. Mist each layer of waste as you add it to maintain the proper moisture level. Shove a compost thermometer in the center of the pile to monitor your compost temperatures.
Allow the wood chip compost to heat up for approximately two to three weeks. Mix the layers of compost together as soon as the compost thermometer begins to register temperatures below 110 degrees F. Shift the organic waste in the center of the pile to the outside edges and move the material along the edges to the middle of your heap. Add fresh layers of wood chips and animal manure to maintain the hot temperatures as the volume of your pile decreases.