Landscaping with a Green Thumb: Composting
Compost is a free gift of nature that all plants thrive on. As a soil amendment or mulch, it improves the fertility and water-holding capacity of soil, encourages healthy root development in plants, and provides food for the microorganisms that help to keep soil in a balanced condition. That is exciting news for the gardener and his garden. However, maintaining a compost pile is also a wonderful favor to the environment beyond the garden walls, since it keeps kitchen and yard waste out of our overflowing landfills. Starting a compost pile is great way to manage your household waste and create a thriving, earth-friendly garden for your family.
Over the years, composting has been honed to a science, with complicated instructions about the types and ratios of materials to use, how to layer them, how to achieve the best temperature in the pile, how to speed up the process, and lots more. You can spend a great deal of money purchasing an efficient, animal-proof compost system, a special thermometer, a tool for aerating the pile, compost starter, and many other products. But the truth is, there is no mystery to composting, and it doesn't have to cost you. "Passive" composting will produce wonderful compost—it just takes longer than "managed" composting. Let's cover the basics.
What Is Compost?
Compost is decomposed carbon-rich materials (such as leaves) and nitrogen materials (such as grass clippings and kitchen scraps). It results from the feeding of hundreds of different organisms, including earthworms, insects, bacteria, and fungi. Almost any organic material is suitable for a compost pile, but the best compost has a good ratio of carbon-rich materials ("browns") to nitrogen-rich materials ("greens"). The right conditions of heat, air, and moisture will speed up the composting process and also generate heat that destroys weed seeds and plant diseases.
Choosing a Site
Your compost pile should sit on bare ground, in a level area with good drainage. If it sits on concrete or asphalt it won't drain properly, nor will earthworms be able to migrate into it to do their work. In the interests of aesthetics—and to avoid upsetting your neighbors, try to find a site that isn't too visible. If you plan to put kitchen scraps in the pile, make it convenient to your back door. If you live in a cool latitude, seek a spot that is sunny as well as sheltered from cold winter winds. If you live in a warm, dry latitude, a shady location will prevent the pile from drying out too quickly.
Creating an Enclosure
In theory, you don't need any sort of enclosure or bin for your compost—it will happen just fine without one. However, the pile will look better and be easier to manage with a three-sided enclosure made of fencing, wood, or cement blocks. Leave openings in the walls of the enclosure to allow air in. The fourth, open side will give you easy access to the entire pile, so you can turn the materials in the pile and extract the finished compost. A bin no larger than 4'x4'x4' is recommended. If you have the room, set up a second bin next to the first—that way you can shift undecomposed materials easily to get to the finished compost.
Of course, you can purchase a compost bin or system from any number of websites and garden centers. Many of these have a locking lid, which prevents animals from foraging and helps to keep down odor. If you live in an urban area, check with your DPW to see whether they offer subsidized bins.
What to Compost
If you start a compost pile in the spring, you'll have all of the warm months to get it cooking. But except for the dead of winter, when little decomposition takes place, you can start a pile in any season.
You should aim for a 25:1 ratio of carbon-rich materials ("browns") to nitrogen-rich materials ("greens"). Too much carbon will slow down decomposition, and too much nitrogen can lead to odor. You can roughly judge the ratio by the weight of the materials. Here's just a partial list of things that can go into the pile:
- All kitchen waste except meat, bones, fish, dairy, and high fat foods (e.g., peanut butter) and oils. Meat, fish, and fatty materials will smell and will attract pests.
- Coffee grounds, paper filters, and tea bags.
- Paper and cardboard—cut or tear into small pieces.
- Wood ashes—note that they are alkaline, which is helpful for acid soils. Do not add the ashes from coal or charcoal briquettes.
- Grass clippings that are free of pesticides and herbicides.
- Pine needles—note that they are acidic, which can help alkaline soils. Chop or shred them to help them break down.
- Manure from any animal except meat-eating animals—their waste may contain pathogens. Also forgo bird droppings.
- Shredded leaves of all kinds, except leaves from eucalyptus and black walnut trees, which are toxic.
- Seaweed—wash the salt off well with a hose before adding seaweed to the pile.
Do not put diseased plants, poison oak, poison ivy, or sumac in the pile. It's also a good idea to dry out weeds on the pavement before adding them.
Help the Pile Cook
The more "managed" your pile is, the faster it will produce finished compost. A highly managed pile or a compost tumbler system can give you garden-ready compost in as little as three or four weeks. If you take the passive approach and simply keep adding to the pile, you will find finished compost at the bottom of the pile in about a year's time.
To help keep your pile cooking, follow these tips:
- Make sure the pile stays hotter than the surrounding air. If it's between 104° and 131°F, it will kill pathogens and weed seeds. A compost thermometer can tell you, but you don't need to invest in one. Just make sure you add enough "greens" (e.g., kitchen waste, grass clippings). And when you do, cover the "greens" with "browns" (e.g., shredded leaves, paper) to reduce flies and odor, and to avoid attracting pests.
- Make sure the pile stays moist, but not too wet. Ideally, it should be as moist as a wrung-out sponge.
- Make sure it gets enough air. You can turn it with a pitchfork once or twice during the summer to aerate it. But it's easy to just push several large sticks or branches down through the pile vertically and give them a shake every now and then.
How to Use Compost
Finished compost will be uniformly brown and crumbly, like soil, but usually contains some brown particles of materials that haven't fully broken down. You can be use this compost as is for mulching, spreading a couple of inches of it evenly on top of the soil around plants. However, if you want to mix compost into your soil to enrich it, it's a good idea to screen it to eliminate the particles; they will continue to decompose, reducing the amount of nitrogen available to plant roots.
Compost tea is a wonderful fertilizer for plants, and it's easy to apply. Simply soak a few shovelfuls of compost for a few hours or days in a bucket of water. Pour the resulting "tea" through a screen or cheesecloth into a watering can and feed your plants. The tea will provide beneficial live organisms and improve the soil, and you'll never have to worry about giving the plants too much of it—it won't burn plants.
Related articles:
The Organic Lawn
The Ornamental Garden
The Vegetable Garden
