In Plymouth, acceptable materials for backyard composting are limited to: Grass clippings; leaves and weeds; wood chips and small twigs; evergreen cones and needles; garden waste; uncooked food and vegetable scraps; and commercial ingredients designed to speed or enhance composting. All materials must come from the property on which the composting occurs. Composting materials must be kept in a container that is:

• At least 3 foot by 3 foot by 3 foot in size unless it is a commercially fabricated bin designed for composting; and must not exceed 5 feet wide by 12 feet long by 5 feet high.
• Constructed of durable materials such as wet resistant wood; block; sturdy metal fencing; or be a commercially built bin designed to contain composting material.
• In the rear yard of the property.
• At least 40 feet from the nearest neighbor's home.
• At least 6 feet from any city park, trail, property line and the resident's house.

Start out with a homemade or purchased composting container. It will speed composting, improve appearances and reduce the possibility of pests. A container for compost is also required by Plymouth’s city code. When placing the container look for:

• A level, well-drained area.
• Accessibility from all sides.
• Accessibility to a convenient source of water.

Note: Hennepin County is selling backyard compost bins. View more information.

Compost starts out as a combination of 25 to 50% nitrogen-rich, “green” materials and 50 to 75% carbon-rich, “brown” materials.

GREENS provide nitrogen. They are the source of protein for the microbes hard at work in the compost pile. Greens include: Green leaves, plant trimmings, raw fruit and vegetable scraps*, fresh grass clippings.

BROWNS provide carbon. They are a source of energy for the microbes. Brown materials include: Dried grass and leaves, straw, wood chips, small twigs and branches, sawdust, corncobs and stalks.

*Raw fruit and vegetable scraps are the only food waste allowed for home compost bins in the City of Plymouth. Meat, dairy products or oils cause odors and attract scavengers like raccoons, rats and neighborhood pets.

How to prepare your materials for backyard composting:

1.  Place four-inch to six-inch of base material such as drive leaves or wood chips on the ground. This will allow air circulation around the base of the pile. (Skip this step if using a compost mixing container).
   
   
2. Alternate  two to four inches of “green” organic material containing nitrogen and four to six inches of “brown” organic material containing carbon. (See above for descriptions of “green” and “brown” material.) Keep a ratio of one part green and two to three parts brown. Keep layers uncompact so air can circulate.
   
   
3. After each green and brown layer add up to one inch of an activator to introduce microorganisms into the pile. Activators such as garden soil or bone meal will provide nitrogen to encourage the reproduction of microorganisms. A pile must have microorganisms to decompose the organic waste.
   
   
4. Water the pile so it’s moist, but not soaking wet. The compost should be damp enough to form a clump, but not drip when squeezed.

Tip: Save a few bags of dry leaves from fall cleanup for a source of brown material for your compost the following summer. 

Insects, bacteria, worms, centipedes, beetles and sow bugs are some of the organisms that turn yard waste and fruit and vegetable scraps into compost. They do their job best when they have adequate air and moisture, along with a mix of nitrogen and carbon materials for food.

Moisture

The compost should have 50 percent moisture content and feel damp like a wrung-out sponge. Test the moisture content by squeezing a handful of the compost. It should form a clump, but not drops of water. Add moisture to the compost pile by either adding green material or sprinkling it with water.

Oxygen

 The pile should be aerated about once a week by:

• Turning the pile, outside to inside or top to bottom.
• Stirring the pile.
• Using an air stack or aerator tool to bring air into the center of the pile or;
• Using a tumbler compost bin to rotate the pile every two to three days.

Surface Area

Increase the surface area to improve decomposition. Shred or cut organic material into smaller pieces.

Temperature

A working backyard compost pile typically heats up to between 90 to 120 degrees Fahrenheit.  If the pile no longer heats up, it may be an indication that the compost is ready for application. If the compost is not ready, follow trouble-shooting suggestions below to improve decomposition.

Finished Compost

With proper materials, aeration and moisture, compost should be ready in about six months. Compost is ready when it has decomposed into small, crumbly, dark brown soil-like particles. When some of the compost is ready, remove the finished compost and then start a new pile.

A properly working pile has a slight earthy smell to it or no odor at all. If that doesn’t describe your compost pile, try the following suggestions:

• To help dry an over-watered pile: Add sawdust, straw or wood chips, or place wood planks underneath the pile to ensure good drainage.
• If the pile is too dry: Turn it over, and add greens and water.
• If the pile is damp, sweet smelling and will not heat up: It needs nitrogen. Turn the pile and add grass clippings, blood meal or urea fertilizer.
• If the pile smells like ammonia: Add brown leaves, sawdust, straw or wood chips.
• If the materials do not seems to be decomposing or heating up: Add nitrogen, turn the pile and maintain 50% moisture.
• If unwanted creatures are interested in your compost: Bury the food waste close to the pile’s center and avoid “items not to compost” below.

The below items are OK to compost: 

• Leaves
• Grass clippings
• Plants
• Nut shells
• Straw & hay
• Fruit & vegetable scraps
• Egg shells
• Sawdust & wood chips
• Flowers

The below items should not be composted:

• Meat & fish
• Dairy products
• Oil or fatty foods
• Bones
• Pet waste
• Diseased plants
• Weeds with seeds
• Ashes or charcoal
• Whole branches
• Chemically treated yard waste

Licensed garbage haulers in Plymouth provide curbside yard waste pickup service to their customers. According to state law, yard waste must be placed in a cart or a compostable bag made of kraft paper or compostable plastic.

Plymouth residents may bring leaves, brush, tree and garden waste to the Plymouth Yard Waste Site. 

New in 2024: Weekly Curbside Organics Collection

The city’s recycling contractor, Republic Services, will now offer weekly curbside organics collection to all Plymouth households beginning in early March 2024.

All households pay for organics recycling through their utility bill, like regular recycling. Residents must sign up to receive an organics cart to get started. Learn more about weekly curbside organics collection.

Hennepin County: How to compost
Hennepin County: Organics (food waste) composting
Recycling Association of Minnesota: Annual low-cost compost bin and rain barrel sale
Minnesota Pollution Control Agency: How to compost (PDF)
Minnesota Composting Council: Composting