Making backyard compost even has a civic benefit because it saves landfill space, helping to keep garbage-processing costs lower for you and your neighbors.

You can make compost without spending a penny, or you can buy simple equipment that looks tidier and speeds up the transformation process. Whichever approach you take, you’ll need to understand a few key principles of composting.

How compost happens

Left alone in a natural habitat, plants create their own compost. Leaves, twigs, and overripe fruit fall to the ground and slowly get broken down into nutrients. You can make this same process happen in an out-of-the-way spot with a compost pile—and distribute the results by sprinkling the compost over planting beds as fertilizer, dropping it into the hole before you set a vegetable plant in the ground, or even using it as mulch.

There are two main ways to compost: You can use only yard waste—or add kitchen waste, too.

Yard waste composting

If you’re composting only yard waste, an open pile is all you need. For the richest, fastest results, alternate layers of green (nitrogen-rich) plant material, such as lawn clippings and plant cuttings, with brown (carbon-rich) material, such as dry leaves. Make the layers approximately equal or add a little more browns than greens.

Cut branches and stems down to 3 to 6 inches long—and skip any that are more than ½ inch thick—unless you’re willing to sift out remaining chunks when you use the compost. Moisten the materials with a garden hose as you add them so they are about as damp as a wrung-out sponge.

If a pile of dead plants would look too messy for your yard, corral the trimmings in a compost bin. You can buy one, but first contact your local solid-waste disposal company or municipal service to ask whether it offers a subsidy for buying a composter—or perhaps even gives them away free.

The Concord Compost Bin, which consists of top and bottom lids and a side wrapping made of flexible plastic perforated with holes, sells as for about $100 to $175, depending on capacity, at composters.com. Or you can make your own from wood and wire mesh following instructions from Seattle Tilth or Lowe’s.

You can make “hot compost” or “cold compost.” Hot composting works faster (usually in three to six months) and kills most weed seeds. But you need to build the whole pile at once and turn it with a pitchfork every month or so to ensure that the stuff at the edges has a turn in the center and vice versa.

For cold composting, you just layer on the materials as you collect them, add water as needed to keep the pile damp, and let nature do the rest. It might look like nothing is happening, but after six to 12 months, when you remove the relatively unchanged top layer, you’ll find compost underneath. You can tell it’s ready if it looks like dark black soil, with no sign of its original form remaining.

With either system, having two bins makes the job easier because you can scoop the contents of one into the other to turn a hot pile, for example, or to expose the compost under a cold pile. Three bins are even better because you can store finished compost in one while you’re working on a new batch in the other two.

Adding food waste

Kitchen scraps are high in nitrogen, so adding them to your compost speeds up decomposition and results in a richer material. Plus, since it counts toward your green materials, which are usually less abundant than brown ones, it allows you to create more compost.

Just don’t put food waste in an open compost pile. That would draw rats, raccoons, and other pests. To make any compost bin rodent-proof, wrap it with metal mesh, called hardware cloth, with quarter-inch openings—including the top and the bottom.

Or you can choose a tumbler-style composter, which consists of a drum that rotates on an axis, so instead of turning a pile with a pitchfork, you simply tumble the drum a few times to mix up the contents.

This system works fast, though if you want finished compost in two to four weeks, as some of their labels promise, you have to shred everything first and turn the tumbler every day or two. Tumblers are also relatively pricey—around $300 to $400 at sites such as People Powered Machines and CompostBins.com. Some large-capacity bins may cost more.

What not to compost

Never put the following into your compost:

  • Weeds, which can survive and sprout again
  • Diseased or insect infested plants, which can infect your garden plants
  • Any plant, including grass clippings if you use weed control products, which was sprayed with a pesticide
  • Dog and cat waste, which can harbor parasites and diseases
  • Meat, which stinks as it decomposes and may contain harmful bacteria that can survive composting
  • Wood ashes, which are too alkaline for some plants