Composting: the process of mixing various decaying organic substances.

Yard Waste

Grass clippings, mulched leaves, wood ashes, straw, lake plants, and dirt all make good compost when in the right proportions. Here is a good recipe for compost:

  • 3 parts dry leaves
  • 2 parts fresh grass clippings

Food Waste

Fruit, vegetables, egg shells, coffee grounds, and bread are great for compost. Here is a simple recipe for compost with kitchen scraps:

  • 3 parts dry leaves
  • 1 part fresh grass clippings
  • 1 part food scraps

The following items should not be composted: pet feces, meat, bones, and dairy products.

Fruit, vegetables, eggshells, coffee grounds, and napkins CAN be composted.


What can be put into a compost bin?
Good materials include grass clippings, fruit waste, wood ashes, livestock manure, mulched leaves, coffee grounds, lake plants, bone/blood meal, straw, eggshells, straw, compost, vegetable scraps, a little sawdust, and dirt.

How long does it take to make compost?
Compost can finish in 6 months to 3 years, depending on the amounts of air, water, carbon, nitrogen, and turning that the materials receive.

How should I fill my bin?
"Layer the compost pile as you add materials to facilitate decomposition by ensuring proper mixing. Each pile ideally should be about five feet high. Put down organic wastes such as leaves, grass, and plant trimmings in a layer eight to ten inches deep. Coarser materials like twigs, stalks, and chipped branches will decompose faster if placed in the bottom layer. Water this layer until moist, but not soggy. A nitrogen source should be placed on top of this layer. Use one to two inches of livestock manure, or a nitrogen fertilizer such as ammonium nitrate or ammonium sulfate, at a rate of one third of a cup for every 25 square feet of surface area. If these nitrogen sources are not available, 1/3 cup of 27-3-3 lawn fertilizer per 25 square feet of surface area will also work. Do not use fertilizer that contains herbicide or pesticide. Other organic sources of nitrogen that can be used are green grass clippings, lake plants, cottonseed meal, or blood meal. Grass clippings tend to mat and should either be mixed well with other materials, such as wood chips or leaves, or placed in layers only one to two inches thick." (University of Minnesota Extension

How big should my compost bin be?
"A pile that is 1 cubic yard (3 feet high, 3 feet wide, 3 feet long) is big enough to retain heat and moisture, but small enough to be easily turned. Home compost piles shouldn't be larger than 5' x 5' x 5'." (MPCA)

How do I know my compost is done?
Compost in Minnesota can finish in 6 months to 3 years. Finished compost will have a granular texture, homogenous color, and neutral or earthy odor.

How should my finished compost look, smell, and feel?
One of the most common reason a backyard compost works slowly or stops composting is a lack of moisture. You should have beads of moisture form between your fingers when you squeeze a handful of composting materials - like a sponge. The compost should have an earthy smell. It should look well mixed.

What can't be put in a compost bin?
Materials such as pet feces, meat, bones, and dairy products should not be composted. The US EPA has compiled a good list of materials that should not be composted.

Why isn't my compost bin working?
The composting process requires brown AND green materials, water, mixing, and temperature. If any of those parts is missing or deficient, your compost bin will not perform at optimum rates. Large particles can inhibit compost activity so consider shredding materials before composting them.

Why does my compost bin smell bad?
Bad smells are typically caused by anaerobic decomposition. Anaerobic conditions occur when oxygen is limited by excess moisture, lack of mixing, or rapid decomposition of green materials. To eliminate odors, try mixing your compost or adding dry materials or brown materials.

How much green and brown materials should I put in the bin, respectively?
3 parts leaves to 2 parts grass is an optimum ratio. You can substitute food scraps for 1 part of grass in a compost bin.

Will a compost bin attract animals?
A compost bin can attract animals, especially if you include materials that cannot be composted, such as meat, bones, and dairy products. You can minimize animal attraction by covering your bin and mixing composting materials with yard waste frequently.

"You can also modify a garbage can with a tight-fitting lid for use as an animal-resistant bin for composting food scraps. All you need to do is drill some holes in the bottom of the can for drainage, set it in a shallow hole so animals can’t tip it over, and cover layers of fruit and vegetable scraps with a 2-4 inch layer of brown leaves or soil to control fruit flies and odors.(Santa Cruz CDPW)

How often should I turn my compost bin?
"Mixing the pile once or twice a month will blend the cold outer edges of the pile into the warmer, more active center of the pile and significantly hasten the composting process. A pile that is not mixed may take three to six times longer before it can be used." (University of Minnesota Extension)

How hot should my compost get?
For a hot compost pile, temperatures must be maintained at 140 degrees F for three days. To reach these temperatures, brown materials must be shredded with a mower or chipped. The main advantage of a hot pile is it composts faster and kills weed seeds. Remember, maintaining a hot pile takes ongoing attention to aeration (turning), moisture, and the balance of green and brown materials.

If you don't have the time or inclination to maintain a hot pile, don't worry. Cold compost piles break down too! They just take a bit longer. Piles made on an add-as-you-go basis heat up very little, even if they are high in green materials, as break down occurs incrementally. You can help a cool pile to heat up by mixing in blood meal, alfalfa hay, or horse or chicken manure.(Santa Cruz CDPW)

Additional Resources

University of Minnesota Extension 2008. "Composting and Mulching: A Guide to Managing Organic Yard Wastes." St. Paul, MN.

Minnesota Pollution Control Agency (MPCA). 2011. "Start composting in your backyard." St. Paul, MN.

Crow Wing SWCD. 2010. "The Who, What, Where, When, Why and How of Composting." Brainerd, MN.

Minnesota Pollution Control Agency (MPCA). 2007. "Diagnosing common backyard composting problems." St. Paul, MN.

US Environmental Protection Agency (EPA). 2011. "Wastes - Resource Conservation - Reuse, Recycle - Composting."Washington , D.C.