Fall is one of the best times to start—or restart—a compost pile. Leaves, spent plants, grass clippings and garden debris are everywhere, and instead of sending them away, you can turn much of that material into something your garden can use next year.

Think brown and green.

Brown materials provide carbon:

* Dry leaves

* Straw

* Shredded paper

* Small woody prunings

Green materials provide nitrogen:

* Grass clippings

* Fresh plant trimmings

* Vegetable scraps

* Coffee grounds

Portland's fall and winter rain can turn a compost pile into a soggy mess.

Your pile should be about as damp as a wrung-out sponge. If it's too wet, add dry leaves or other brown material. During the rainy season, covering the pile can help keep excess water out.

Turning the pile introduces oxygen and helps everything break down more quickly. You don't have to obsess over it, though.

A simple cold compost pile can work with much less effort—it just takes longer.

Keep these out of your backyard pile:

* Meat and dairy

* Oils and fats

* Pet waste

* Diseased plants

* Weeds loaded with seeds

Kitchen scraps can also attract rats and other unwanted visitors, so use a covered bin if you're adding food waste. 

Finished compost should be dark, crumbly and earthy-smelling.

For existing garden beds, a thin layer—roughly ¼ to 1 inch per year—is generally enough. For a new vegetable bed, we recommend about 3–4 inches worked into the soil.

Don't go overboard. More compost isn't necessarily better, and excessive applications can create nutrient and water-quality problems.

Don't throw those fall leaves away. They're one of the best—and cheapest—ingredients you have for building better garden soil.

Save a pile of dry leaves next to your compost bin. You'll have a ready supply of “browns” whenever the pile gets too wet or green.