Frequently Asked Questions

It is likely that your compost contains mainly nitrogen-rich materials like kitchen scraps or grass clippings. Food scraps have a high moisture content and your compost is fermenting due to the absence of oxygen in a waterlogged situation. The products of fermentation include ammonia-like substances and hydrogen sulfide (smells like rotten eggs).

To remedy this, add carbon and oxygen and reduce moisture. By adding a large volume of dry leaves, shredded newspaper or sawdust, and aerating your pile with a spading fork, you will correct the imbalance of brown (carbon) and green (nitrogen) materials.

Aim for a moisture level in your compost pile that feels like a damp wrung-out sponge.

If your pile is less than 3 cubic feet in volume, it needs more mass to compost effectively - so build a bigger pile.

Your pile might have too much carbon and not enough nitrogen. Nitrogen materials are often wet (food scraps, grass clippings), so mixing them into dry carbon materials helps add moisture. Add water, if needed, so the moisture level feels like a damp wrung-out sponge.

Strive for a C:N (carbon to nitrogen) ratio ranging between 25:1 and 30:1. Good carbon materials are leaves, shredded straw, shredded newspaper, wood shavings, saw dust. Good nitrogen materials are grass clippings, food scraps, herbivorous animal bedding, plant debris.

Monitoring your pile temperature and turning it whenever it dips below 110 degrees keeps your pile active for the fastest breakdown.

Chopping up your materials into smaller particle size improves the rate of decomposition. Organic materials can be chopped, shredded, split, bruised, or punctured to increase their surface area. Don’t ‘powder’ materials because they will compact and impede air movement in the pile.

Do not add meat or bones, dairy, oils, peanut butter, sauces or salad dressings, to your compost pile.

A pile that is too dry and not turned very often can make an attractive nesting place for mice. If you see a mouse, try making your pile wetter and turn it every day for a week to discourage nesting.

Mice and rats love to live in thickets of plants that never get disturbed and that provide year-round shelter. Do not place your compost bin in an area overrun with ivy or similar brush.

To avoid attracting bears, dig fruit and vegetable scraps deep (12 inches - 18 inches) into the center of your compost pile, rather than leaving them on top where they are easily detected by bear’s noses. Top your pile with a thick layer of brown carbon-based material like leaves.

1. Cease adding bear attracting foods to your bin and top off the bin with brown carbon materials.
2. Check your home and yard to avoid becoming an easy food source for bears. Bears are attracted to bird feeders, improperly stored garbage or recycling with food residue, fruit trees with fresh or rotting fruit, pet food kept outdoors, uncleaned barbecues, fresh grass clippings.
-Do not put out your garbage until the morning of pickup.
-Freeze odorous foods (such as meat, skin, bones, seafood) until morning of pickup.
-Keep your garbage container clean.
-Properly secure food in trash bags to restrict odors.
3. Empty the existing compost and dig it deep into a garden.
4. Start again and ensure that whenever “greens” (nitrogen-based material) are added, they are buried under a layer of “browns” (carbon-based material).

If you know bears regularly explore your neighborhood, do not compost bear attracting foods like meat, fish, eggs, whole or rotten fruits, grains, oils.

Harvest your fruit trees immediately, or just before the fruit ripens. Pick up fallen fruit immediately. You can compost 1 or 2 fruits by burying them deep into your pile, covering them with carbon-rich material. Use pit or trench composting to deal with greater numbers of fruit by digging a deep hole in your garden and burying the fruit under no less than 12 inches - 18 inches of soil, where it will compost underground.

Insects are a sign of a productive compost pile. If there is an abundance of flies, bury your food scraps as least 8-12 inches deep into the pile. Keep a layer of dry leaves or grass clippings on top of the pile. Thermophilic temperatures in your compost pile will kill fly larvae.

Yes, only if you are using a ‘hot composting’ method, which involves mixing in a good recipe of materials all at 1 time for a volume of at least 4 cubic feet, turning frequently, maintaining correct moisture levels - in order to obtain a pile temperature of 130-150 degrees for 7 consecutive days, which is sufficient to kill weed seeds, plant pathogens and invasive weeds with rhizomatous root systems.

Most backyard composters use a ‘cold composting’ method, which involves adding materials incrementally as they become available. Cold piles are ineffective at reliably killing weed seeds, plant pathogens and weeds with rhizomatous root systems.

Try cooking weed seeds, diseased plants and invasive weeds using the heat of the sun: place weed seeds and plants in a clear plastic bag with some water and seal tightly, lay out in hot full sun for at least 1 week until putrid. Then add to compost pile.

Or instead, burn them in a safe location, then add the cold ashes to your compost pile.

Weeds contain many nutrients that you can use to fertilize your plants. Try this method: Create a dedicated ‘weed bucket’ to drown weeds by filling a bucket with water and weeds, let weeds steep till liquefied. The weeds will anaerobically decompose (become smelly) and the resulting green liquid can be used directly in the garden as fertilizer.

The temperature of finished compost should be the same as the outside temperature, and the material should not reheat. You will see earthworms and other insects now that the temperature is lower. If your compost is still hot, smells like ammonia, or you can still recognize much of the original material, then it is not ready to use. Once the compost appears finished, let it sit for at least 3 weeks to make sure decomposition has stabilized.

Compost is ready to use when it is dark, brown, crumbly, sort of fluffy, with a pleasant, earthy odor. It would not be moldy or rotten. The original materials that went into the pile should no longer be recognizable, except for some woody pieces, which you can throw back into your next compost pile.

You might be tempted to use compost before it is ready, but don’t do it. If incompletely decomposed material is added to your garden soil, bacteria may compete with plants for nitrogen in the soil. Plants will look stunted and yellow. Unfinished compost has been found to also retard germination and growth of seedlings.

No. Pesticides and herbicides are designed to kill insects and will have a negative effect on the health of your compost pile, killing the very critters that you are relying on to break down your organic materials. Studies have shown that pesticides and herbicides persist in compost, and do not become neutralized through the process of composting.

Choose animal bedding or manure from herbivores. Hot composting methods will ensure that weed seeds and pathogens will be killed. Avoid using manure or bedding from animals that have been treated with de-worming medication, as this is harmful to the insects needed for composting.

To compost dog waste and cat litter and feces, use a dedicated, below-ground pet waste composter, also called a digester. Find more information on the

Eggshells add valuable calcium to compost, but take a long time to break down. Try crushing them into smaller bits, or grinding them with a mortar and pestle, to speed up the process.

Most people let their pile shut down in the winter and reactivate it in the spring.

Try vermi-composting with your food scraps using a worm bin in your basement. Learn about vermi-composting and how to make your own worm bin. Get more information about