May 4 through 10 is International Compost Awareness Week, aimed worldwide to raise public awareness on why we all should compost our organics and use compost in our yards and gardens to create healthier soil.
This year, the Piedmont Master Gardeners are doing their part by launching free workshops on how to recycle home and yard waste into compost—to turn your garbage into gold. The outdoor classes showcase best options for composting in a range of settings, from small urban spaces to large rural properties. Geared to meet the needs of a wide audience, from families with children to adults of all ages, our workshops emphasize how every household can keep compostable waste out of landfills. Consult our Events page for future offerings.
Why Is This Important?
According to the Environmental Protection Agency, the U.S. sends more than 292 million tons of solid waste to municipal landfills in a single year. Over 50 percent of this waste is compostable, with food scraps alone accounting for more than 21 percent. When added to a landfill, food scraps decompose anaerobically (without oxygen) and release methane, a potent greenhouse gas that contributes to global warming. When composted and applied in the garden, food scraps contribute to healthy soil and plants and to cleaner water and air.
What Is Composting?
The composting process involves combining carbon-rich waste (fallen leaves, straw and woodchips, for example) and nitrogen-rich waste (food scraps and grass clippings, for instance) in the right proportions and with the right mix of air and moisture to promote decomposition. The result is a dark, earthy-smelling humus that is ideal for improving soil structure. When added to soil, compost enhances water penetration and drainage, boosts plants’ ability to take up water and nutrients, helps plants resist pests and disease, and reduces the need for chemical fertilizers.
Home Composting Basics
To compost at home, choose a convenient spot where appearance and possible odors are least disruptive to neighbors. A manageable batch size is a 3-to-4-foot cube, large enough to heat up (more about that below) but small enough to mix and moisten.
Start with a few inches of wood chips or other rough vegetation at the base for aeration and drainage. Mix high-carbon organic materials (Browns) with high-nitrogen organic materials (Greens) at a Brown to Green ratio of 3:1 by volume. Chopping these materials into smaller pieces will speed decomposition. Keep the pile moist, but not drippy. Add moisture as needed. Mix the pile at least weekly to keep it aerated, and move materials through the pile center for quicker decomposition.
What Should Go into Your Batch
Brown compostables include:
• Leaves, preferably chopped
• Wood chips
• Straw
• Shredded paper (not coated)
• Sawdust (not pressure treated)
Greens compostables include:
• Grass clippings and weeds without seeds
• Fruit and vegetable food waste
• Crushed eggshells (not eggs)
• Coffee grounds
• Manure (not pet waste)
Never add these to a home compost batch:
• Meat, grease, bones
• Diseased, treated or invasive plants
• Weeds and hay with seeds
• Non-organics such as plastic, glass and metals
• Any material that might contain residual pesticides/herbicides
Also, avoid putting black walnut leaves or chips into your compost. Black walnut trees produce high concentrations of juglone, a chemical known to inhibit the growth of some plants.
Hot vs. Cold Composting
The Hot Composting process starts with the right mix of Browns and Greens (again, 3:1 by volume), moistened and aerated. In these proportions, the batch should heat up to more than 130 degrees F—hot enough to kill most weed seeds, harmful insects and eggs, and disease organisms.
If the pile fails to heat up, add Greens and moisten. If it smells like ammonia, add Browns and turn the pile. The batch will start to cool after a few weeks. Maintain moisture, and keep turning the pile to aerate.
Over several months, decomposition will reduce batch size as particles get smaller. When the compost reaches a deep brown color and the starting materials are no longer recognizable, it’s ready to be sifted through a screen and used in the landscape. Any remaining big pieces can go into the next batch.
Cold Composting is slower but easier. Like Hot Composting, it avoids the harmful impacts of landfilling yard and kitchen waste. First, make a pile of leaves, straw or other Brown and Green compostables, and add more as they become available. It’s that simple. The batch won’t get hot and will take longer to break down, but it will decompose into compost. Be sure to avoid adding weed seeds.
For more details and resources, take a look at this Virginia Cooperative Extension publication, “Making Compost from Yard Waste.” Other methods include vermicomposting, an indoor option that uses earthworms to break down organic waste. Learn more at this EPA website.
Helping Our Community Recycle Waste
The Piedmont Master Gardeners promote home composting as part of a partnership formed by the Thomas Jefferson Planning District Commission to help meet the district’s recycling goals. Piedmont Master Gardeners also serve as compost educators in several Albemarle County elementary schools, helping students place appropriate school lunch waste in bins for compostable materials.