It is the perfect time of year to talk about composting. Leaves have begun to fall, and gardeners are cleaning up and cutting back spent flowers and other plant material in the garden.

Composting this material is the ultimate step in sustainable gardening — returning nature’s bounty to our garden soil. I have been an enthusiastic composter for the past 10 years and have watched as my gardens thrive and my carbon footprint shrinks.

Compost is produced when organic matter such as garden, lawn and other organic waste is broken down by bacteria and fungi. Compost incorporated into your garden soil can reduce erosion and water runoff. Plant roots penetrate compost-rich soil more easily and hold the soil in place. Water then flows down into the lower soil layers, rather than running off into the stormwater system.

Compost provides food for earthworms, soil insects and beneficial microorganisms, and contributes to the production of healthy plants that are less susceptible to diseases and insect pests. 

I have composted lawn clippings, plant material which is not diseased, uncooked vegetables and fruit peelings, cat and dog fur, hair, coffee grounds, tea leaves, egg shells, lint from the dryer and the refuse from my vacuum cleaner. The resulting organic matter is black gold for my garden.

In the past 10 years, the trash I bag for pickup by the county has been reduced by half, and almost all the uncooked organic matter from my kitchen and garden has been turned into a nutrient-rich compost for my garden soil. 

And I am a lazy composter. I don’t have room to use the ideal three-sectioned compost system, consisting of a separate bin for each stage of the compost process — a bin for fresh plant refuse, another for the actively composting pile and a third for the finished compost. This system allows the composter to turn the pile frequently, thus exposing garden debris to air (essential to the rapid decay of organic material).

My composter is a large, three-tiered bin made of recycled plastic that I bought at a big box store. When it’s time to turn the pile, I take off each section, and rebuild the bin in an adjacent spot, moving the top compost to the bottom of the newly built bin and removing the bottom layer of composted material. It takes a bit longer for my plant materials to decompose (about six months), but the ease of this system suits me. The compost that is produced is moist, dark and rich in nutrients. Since I add coffee grounds every morning, the resulting compost is redolent of coffee.

A compost pile can be as plain or as architecturally intricate as you want. A gardening friend of mine has an open pile in the driveway off the kitchen addition of her house. She lobs kitchen scraps out the door and carts debris to the pile from the garden. Another friend has built a series of wooden bins covered with a shingled roof and has grown ornamental vines across the roof.

The important thing is the size and location of your compost pile. Compost piles smaller than 27 cubic feet (3 feet by 3 feet by 3 feet) do not heat up sufficiently for effective composting, and piles larger than 125 cubic feet (5 feet by 5 feet by 5 feet) do not allow sufficient oxygen to reach the center. So take care that your compost pile falls somewhere between these two sizes. And take care that the pile is situated on a well-drained site.

Good compost is comprised of four important elements:

1. Organic material in a specific carbon/nitrogen ratio: that is, 25 parts carbon material to one part nitrogen. To simplify — four parts brown material (e.g., dry leaves, egg shells, woody plant material and dryer lint) to one part green material (e.g., manure, green leaves, vegetable/fruit peelings, coffee grounds and tea leaves).
2. Microorganisms: a shovel full of good garden soil or manure.
3. Moisture: the pile should feel like a moist sponge.
4. Oxygen: this is essential to the breakdown of organic material. The more you turn the pile, the faster the organic material decomposes.

Organic materials that you should never add to your compost pile include meat, fish and animal fats such as butter or oils. These attract unwelcome visitors, including mice, rats or raccoons. Barbeque ashes and dog or cat feces can pose health risks.

Prospective composters might fear that a compost pile or bin will reek as the material decomposes. My bin is located off the front driveway, and I have never had a problem with unpleasant odors.

Unpleasant, ammonia-like smells signal that the compost is either too wet or too tightly packed for oxygen to circulate. The cure is to turn the pile and add “woody” materials like thin branches or dried stems to increase the air space between the layers of organic material.

There are many types of ready-made compost bins. Some come with handles that allow you to spin the composter to aerate the compost pile. Autumn is a good time of year to start your compost pile. It's the season when fallen leaves can be crushed and easily added to the pile, and it's the season when garden centers and big box stores reduce the prices of the composters in stock. 

If you are interested in seeing a large variety of composters in action, take a trip to River Farm on the George Washington Memorial Parkway. The American Horticultural Society has a large number of demonstration composters available for public view on site.

If you want to improve the soil in your garden without having to purchase fertilizers or other chemical additives, reduce the amount of waste sent to the landfill or dump and reduce water runoff that contaminates our watershed, I highly recommend composting. There’s something extremely satisfying about returning the products of our garden to the earth and knowing that this compost will ensure that next year’s garden will be healthy and bountiful.

Eleni Silverman is a Master Gardener, Vice President of the Belle Haven Garden Club, Chair of the Landscape Committee at Thomas Jefferson High School for Science and Technology and author of the garden blog "Belle Haven Garden Maven." She is sole proprietor of The Well Tended Garden, providing garden grooming, coaching and design. She admits to a fascination with all things gardening, believes even compost is engaging, and will eagerly discuss the relative merits of leaf mold versus hardwood mulch.