Composting Guide: Turn Waste into Garden Gold
Composting transforms kitchen scraps and yard waste into one of the most valuable soil amendments for your garden. Finished compost feeds the soil food web of beneficial microorganisms, improves soil structure for better drainage and aeration, provides slow-release nutrients that plants use throughout the growing season, reduces the need for synthetic fertilizers and water, and keeps organic waste out of landfills.
What to Compost
Brown materials rich in carbon provide energy for composting microorganisms. Brown materials include dry leaves, straw, hay, wood chips, sawdust, shredded paper, cardboard, pine needles, and woody plant prunings. Shred or chop brown materials into small pieces for faster decomposition.
Green materials rich in nitrogen provide protein for microbial growth and reproduction. Green materials include kitchen scraps like fruit and vegetable peels, grass clippings, fresh plant trimmings, coffee grounds, tea bags, manure from herbivores like cows, horses, rabbits, and chickens, and green leaves. Chop or shred green materials to increase surface area for microbial activity.
The ideal carbon to nitrogen ratio for fast, hot composting is roughly twenty-five to thirty parts carbon to one part nitrogen by weight. This ratio balances microbial food needs for efficient decomposition without odor problems. Too much carbon slows decomposition. Too much nitrogen causes ammonia odor and nutrient loss. A good rule of thumb is two to three buckets of browns for every bucket of greens.
What Not to Compost
Avoid meat, fish, bones, dairy products, fats, and oils that attract pests, create foul odors during decomposition, and decompose slowly in home compost systems. Avoid diseased plant material and weeds that have gone to seed, as these can survive low-temperature composting and spread disease or weeds when applied to the garden.
Avoid pet waste from dogs and cats, which can contain harmful pathogens that survive home composting temperatures. Avoid invasive weeds like bindweed, quackgrass, and Bermuda grass rhizomes that survive composting and spread when the compost is used in the garden. Avoid glossy paper, colored ink, and coated cardboard that may contain heavy metals or other contaminants.
Building a Compost Pile
Choose a location with good drainage and convenient access from both the kitchen and garden. A level, well-drained spot in partial shade works well, keeping the pile moist without becoming waterlogged. Full sun dries the pile too quickly, while deep shade keeps it too cool for active composting.
Build or buy a compost bin to contain the pile. Open bins allow good air circulation and are easy to turn. Enclosed tumblers, dual-chamber bins, and wire mesh cylinders all work well. The pile should be at least three feet in each dimension to generate enough internal heat for active composting. Piles smaller than three cubic feet do not heat up enough to decompose quickly.
Layer brown and green materials as you build the pile, starting with a four to six inch coarse brown layer for air circulation at the bottom. Alternate brown and green layers in roughly three to one proportion by volume. Water each layer as you build so the pile is as moist as a wrung-out sponge.
Managing the Compost Process
Turn the pile every one to two weeks to provide oxygen for aerobic decomposition, redistribute moisture and materials from the edges to the center where it is hottest, and expose all material to the high temperatures in the core. More frequent turning produces faster compost. Less frequent turning produces compost more slowly with less effort.
Monitor moisture levels and add water or dry browns as needed. The pile should feel like a wrung-out sponge when squeezed. Dry piles do not decompose. Wet piles with poor aeration go anaerobic and produce foul odors. Cover the pile in rainy weather to prevent waterlogging and in dry weather to conserve moisture.
A well-managed hot compost pile reaches internal temperatures of 130 to 160 degrees Fahrenheit within a few days of building. These temperatures kill weed seeds and plant pathogens. Use a compost thermometer to monitor internal temperature. Turn the pile when temperature drops below 110 degrees Fahrenheit to reintroduce oxygen and restart the heating cycle.
Using Finished Compost
Finished compost is dark, crumbly, smells like rich earth, and does not resemble the original materials. The composting process is complete when the pile no longer heats up after turning and the material has a uniform texture. Maturation takes one to four months for hot compost and six to twelve months for cold compost.
Apply compost as a two to three inch top dressing to garden beds each spring and fall. Work compost lightly into the top few inches of soil. Use compost as a side dressing around growing vegetables during the season. Brew compost tea by steeping finished compost in water for twenty-four to forty-eight hours and use the strained liquid as a nutrient-rich foliar spray and soil drench.
Using Compost in the Garden
Apply mature compost as a soil amendment before planting to improve overall soil fertility and structure. Spread a two to three-inch layer of compost evenly over garden beds and work it lightly into the top few inches of soil in spring before planting. For new garden beds being established, incorporate up to four inches of compost into the soil to build a strong fertility foundation for the first growing season.
Side-dress growing plants with compost during the season for an extra nutrient boost. Place a one to two-inch layer of compost around the base of heavy-feeding plants like tomatoes, peppers, corn, squash, and cabbage when they begin active growth and again when they start flowering and fruiting. Apply side-dressing compost carefully to avoid piling it against plant stems, which can cause stem rot and provide hiding places for pests.
Use compost as a mulch around established plants and trees. Apply a one to two-inch layer over the root zone, keeping it several inches away from trunks and stems. Compost used as mulch provides slow-release nutrients, moderates soil temperature, conserves moisture, and suppresses weed growth. Compost mulch breaks down faster than bark or wood chip mulches and needs more frequent replenishment but provides superior soil nutrition benefits.
Brew compost tea for a liquid fertilizer that delivers soluble nutrients and beneficial microorganisms directly to plant leaves and roots. Fill a five-gallon bucket one-third full with mature compost and add dechlorinated water to the top. Steep for twenty-four to forty-eight hours, stirring occasionally. Strain the liquid through cheesecloth or a fine mesh strainer and use the tea as a foliar spray or soil drench within a few hours for maximum microbial activity.
Troubleshooting Common Compost Problems
A compost pile that smells like ammonia has too much nitrogen-rich green material and not enough carbon-rich brown material. Add more dry leaves, straw, shredded paper, or wood chips to balance the carbon to nitrogen ratio. Turn the pile to incorporate the browns throughout and provide oxygen to the microorganisms. The ammonia smell indicates nitrogen is being lost to the air instead of being captured in the compost.
A foul rotten egg smell indicates anaerobic conditions where oxygen is not reaching the center of the pile. Turn the pile immediately to introduce oxygen. Check moisture levels and add dry brown materials if the pile is too wet. Make sure the pile is not too large or too compacted for air to reach the center. Adding coarse materials like small twigs or straw at the bottom and throughout the pile creates air channels for passive aeration.
A compost pile that is not heating up may be too small, too dry, or lacking enough nitrogen-rich green material. Piles need to be at least three feet in each dimension to retain heat. Add water if the pile is dry, aiming for the consistency of a wrung-out sponge. Add more green materials like grass clippings, kitchen scraps, or fresh plant trimmings to boost nitrogen levels. Turning a cold pile often reactivates it by bringing oxygen and moisture into the center.
Pests in the compost pile including rodents, raccoons, and flies indicate the presence of inappropriate materials. Remove any meat, dairy, fats, or cooked food scraps from the pile. Make sure the pile has adequate brown material covering any fresh kitchen scraps. Use an enclosed bin with a secure lid to exclude larger pests. Bury fresh kitchen scraps under at least six inches of brown material in the center of the pile to reduce accessibility to pests and mask odors that attract them.
Frequently Asked Questions
How long does it take to make compost?
Hot compost with regular turning can be ready in one to four months. Cold compost without turning takes six to twelve months or longer. The speed of composting depends on pile size, material composition, surface area of materials, moisture level, aeration frequency, and ambient temperature.
Why does my compost pile smell bad?
Bad smells indicate anaerobic conditions from too much moisture, too many green materials without enough browns, or lack of oxygen. Add more dry brown materials like leaves, straw, or shredded paper. Turn the pile to add oxygen. Reduce watering if the pile is waterlogged. Cover the pile in rainy weather.
Can I compost in winter?
Composting slows dramatically in cold weather but does not stop completely. Continue adding kitchen scraps to the pile through winter. Build a large pile in fall that generates heat through winter. Insulate the pile with a thick layer of straw or a compost blanket. The center of a large, active pile stays warm enough to continue decomposing even in freezing weather.
Do I need to add compost activator or starter?
Compost activators are not necessary and provide minimal benefit for most home composting. Garden soil or a shovelful of finished compost added when building a new pile introduces the same beneficial microorganisms that commercial activators provide, at no cost and with the same results.
How do I know when compost is ready to use?
Ready compost is dark brown, crumbly, has a pleasant earthy smell, and original materials are no longer recognizable. It should not heat up again after turning and moistening. To test, place a handful in a sealed plastic bag for three days. If it smells sour or ammonia-like at the end, it needs more time to mature.
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