No garden is complete without a compost pile! Compost is a soil conditioner, mulch and fertilizer all wrapped into one. It feeds the soil microorganisms that help plants stay healthy, adds nutrients to the soil, and helps clay soil drain better and sandy soil retain water. Plus, composting reduces your contribution to the waste stream by recycling yard and kitchen waste into the world's best soil amendment. Here's how to build a pile that breaks down fast and never smells bad.

Choose a site that is handy to your garden and kitchen, yet out of plain sight.

You don't need a bin to make compost-a pile of leaves, grass clippings and other yard wastes will do-but a bin keeps the compost contained and looks neater. You can corral compost in a simple wire column made from a 4-foot wide by 8-foot long piece of stiff wire mesh.

You can also buy a more permanent bin or build a three-bin compost system made from slatted wood or recycled pallets. Leave the bins open on one side so you can add compost materials and turn the pile easily. Cover the top of the bins with a sheet of plywood if you live in a very rainy climate. A three-bin system allows you to turn the compost from one bin to another and store finished compost until you are ready to use it.

The two basic elements that make up compost are green garden debris (grass clippings or old annuals) and brown garden derbis (dry leaves). Green ingredients are high in nitrogen and brown materials are high in carbon. Adding too many greens can make the pile smell bad. Do not add animal waste, meats, oils, dairy, diseased plants, weeds that have gone to seed, or plants treated with pesticides or herbicides to your compost.

Compost piles with a balance of one part green to two part brown materials break down fastest. The easiest way to achieve this balance is to add one garden forkful of green material to the pile, top it with two forkfuls of brown material, and mix them together. Continue adding greens and browns until the pile is at least 3 cubic feet (3 ft. x 3 ft. x 3 ft.). Piles of this size heat up quickly and break down faster.

Add in a shovelful of finished compost or garden soil to help kick start the microbial activity in your pile.

Compost also needs the correct amount of moisture to breakdown. Compost with the right moisture level should feel like a damp, wrung-out sponge. Too much moisture can cause temperatures to fall within the pile (and make it smell). Too little moisture slows down the decomposition rate and keeps the pile from heating up. Check your compost pile's moisture level once a week and adjust it if necessary by adding water to increase moisture or more browns to help dry the pile out.

Turn the pile once a week to move material from the outside of the pile in. Turning also keeps the pile from compacting, which reduces airflow and slows down decomposition.

You should have finished compost in about two months. You'll know your compost is finished when it no longer heats up and you can't identify any of the original materials. The compost should be dark brown, moist and earthy smelling. Dig finished compost into your garden's soil. You can use partially composted material as mulch.

You can also build a very basic, passive compost system by simply piling up leaves, grass clippings and other yard waste into a pile in a secluded corner of your yard. The compost will be ready when the original ingredients are unrecognizable, usually in about 6 to 12 months. Compost at the bottom and middle of the pile typically "finishes" first.