What is Compost? 

Composting is a controlled, aerobic (oxygen-required) process that converts organic materials into a nutrient-rich soil amendment or mulch through natural decomposition. The end product is compost – a dark, crumbly, earthy-smelling material. 

Why Compost?

Composting is nature’s way of recycling. It is one of the most powerful actions we can take to reduce our trash, address climate change, and build healthy soil. By composting our food scraps, certified compostable items, and yard waste, we can transform our waste streams into a beneficial, value-added soil amendments and protect the environment. Composting can:

Save Money

  • Composting can be easier and cheaper than bagging organic wastes and having them removed.

  • Your water bills may drop too since a soil that’s well-amended with compost holds moisture better and reduces run-off. 

  • By reducing your trash cart size (e.g. downsizing from a 64 or 96 gallon trash cart, you can save money by using a compost cart for items that can be composted).

Reduce Waste: composting reduces the volume of materials that might otherwise be disposed in landfills or trash incinerators - leaves, grass clippings, yard trim, and food scraps – and preventing  greenhouse gases from being emitted into the atmosphere.

Valuable Soil Amendment: It is more cost-effective to keep materials on site and cycle them back into the yard as a rich soil amendment – compost.

Making a Healthy Garden: your garden will benefit as well. As the health of your soil improves so will the health of your plants.

Learn about more benefits of composting from Eco-Cycle here

Compost Options

  1. Curbside Composting: Best for everyday food waste and compostable items through collection by a pick-up service 

  2. Backyard Composting: Best for organic waste and gardening with a pile/bin in your backyard

  3. Both: Yard waste can be used for gardening and many food scraps and items can be taken by a service provider 


Things to keep out of the compost bin



464 Compost Bin Illustrations & Clip Art - iStockCurbside Compost 

What goes in curbside compost: 

ONLY Acceptable Items 

Always check with your pick-up service provider, but items that can go in your compost cart include:

  • Food scraps including meat and bones 
  • Yard waste
  • Place all items LOOSE in your compost cart, unbagged. That’s it! 

The Following items are NO LONGER ALLOWED 

  • NO BAGS will be accepted, including compostable bags. The only exceptions will be 3-gallon countertop CMA– approved certified compostable bags and brown kraft yard bags accepted for specifically announced spring and fall collection events ONLY. 
  • Paper towels, tissues, coffee filters, colored paper, and other paper-based materials
  • Greasy pizza boxes
  • Certified compostable paper plates and cutlery and service-ware that have the following logos:
    • BPI 
    • Eco-Products that are BPI Certified
    • Products with ”PLA 7” recycling symbol
    • NatureWorks, LLC/Ingeo

Check out Eco-Cycle's Guide for more information 

FOOD-ONLY-compost-guidelines_Businesses-and-OfficesWHY ARE COMPOST GUIDELINESS CHANGING?

A1 Organics is enforcing these new guidelines along the Front Range with all haulers and municipalities they serve due to increased contamination in the materials collected from businesses and residents. Although this material affects only a small percentage—less than 10%—of A1 Organics’ compost products, it is the most challenging percentage in terms of contamination. More than 90% of the organics A1 processes comes from clean sources. A1 Organics is making these changes in an effort to create a high-quality finished compost product from materials generated from municipal collections.

The challenges these new guidelines are addressing are: 

  • Plastic, glass, metals, latex gloves, masks, etc., are mistakenly placed into compost bins and ultimately end up in A1’s finished compost product. Food scraps and yard & plant trimmings make excellent compost, but contaminants like plastic, glass, and metal break down into sharp pieces and/or microplastics that destroy the compost’s value, leaving A1 with a product they cannot sell.
  • Plastic and plastic-coated paper products such as cutlery, tableware, cups, and straws have added to the volume of contamination A1 receives due to misleading and confusing labeling on products that are not compostable but look like they are. For every truly compostable product you might come across, there are several more “look-alikes” that mislead customers into thinking these items are compostable, when in truth they often contain noncompostable plastics.
  • Compostable bags often contain and conceal noncompostable contamination.
  • Not all “certified” compostable products break down into compost as fully or as quickly as composting manufacturers need them to. This is because certification standards test compostability based on laboratory conditions. Those conditions are not always replicated in the real conditions of the compost manufacturing facilities where they may not fully compost. The result is a finished compost product that is contaminated with bits of partially degraded “compostable” material. 

WHERE: A1 is not the only compost manufacturer making these changes. A high percentage of programs, including others in early-adopter composting communities, such as Portland, Seattle, Vermont, and California, are doing the same as the demand for quality compost increases and more communities understand the value of keeping organic materials out of our landfills.

Questions? Visit our Clean Compost Campaign FAQs here

Backyard Compost

Backyard composting requires a little bit of space, a bin, and a basic understanding of the composting process. Compost provides a long-term source of many nutrients not typically found in Colorado’s soils. Compost also helps your soil hold water longer.

See the EPA’s guide on backyard composting to get started

What to include in backyard composting:

Greens (Nitrogen-rich) 

Browns (Carbon-rich) 

Fresh grass clippings

Dry leaves

Garden trimmings

Dried grass clippings

Fruit and vegetable scraps

Hay or straw



Coffee grounds & filters

Shredded paper

Tea bags

Finely chopped wood chips & bark

Manure (plant eaters only)

Old potting soil

What NOT to include in backyard composting:

  • Meat, fish, poultry and bones

  • Dairy products, oils, grease, and fat

  • Weeds with seeds 

  • Pet (dog and cat) waste

  • Charcoal or  Duraflame® ashes

  • Treated wood products

  • Cat litter

Remedies for when your pile Is not compostingfull-backyard-compost-bin

What if…

Possible Cause

Suggested Remedy

Pile not composting

Too dry

Add water until slightly damp and turn

Pile not composting

Too much brown matter

Add fresh green matter (see chart above) and turn pile

Pile smells rotten and/or attracts flies

Too wet and/or too many food scraps or lawn clippings

Add brown material (see chart above), particle size of 1-2 inches will keep pile from matting down

Pile smells rotten and/or attracts flies

Not enough air

Turn it

Animals in pile

Not maintaining or turning pile

Bury food wastes and keep pile maintained and turned

Compost is damp and warm in the middle but no where else

Pile is too small

Collect more material and mix the old ingredients into the new pile

Center of the pile is dry

Not enough water

Moisten materials while turning the pile

Nothing is happening

Pile won’t heat up

May need moisture and more greens such as coffee grounds to kick-start the process again

Wintertime Composting:

Wintertime doesn’t have to bring a stop to composting your food and yard scraps. The process through which composting happens (microorganisms eating decaying organic matter) doesn’t stop during cold weather, but it does slow down. Learn how to weatherize your pile here!

Using Your Compost

Compost is ready for use when it is dark brown, crumbly and when the individual ingredients/items are not recognizable. You can use compost in two stages:

Finished Compost (all particles are broken down):

  • Use as a soil amendment in gardens (anytime)

  • Use as an ingredient for potting soil

  • Place around plants, trees, or on lawns as a mulch or top-dressing

Partially Finished Compost (all particles are not completely broken down):

  • Place around plants, trees, or on lawns as a mulch or top-dressing

  • Spread compost in your garden in the fall so it will enrich the soil over the winter to help your spring planting

Source: https://bouldercounty.gov/environment/composting/back-yard-composting

Compost Tips and Tricks:

Curbside Composting’s No. 1 Contaminant: Plastic

Plastic does not belong in curbside compost bins. When processed in massive compost piles, plastics break down into smaller and smaller pieces, and negatively impact our underground ecosystems, making their way into soils, the food chain, groundwater, and even our bodies.

How does curbside composting work? 

Curbside compost goes to an industrial composting facility, where tons of organic materials like food, low-grade paper, and compostable products are able to decompose in massive windrows that reach 131–170 degrees Fahrenheit. This high heat breaks down many of the items that can’t break down in your backyard compost pile, like plant-based compostable cups and plates. This compost process also destroys pathogens, making it safe to compost used paper towels, tissues, and even bones. Within four months of reaching an industrial compost facility, your leftover food can be returned to the earth to feed plants or improve degraded land. Westminster’s compost is sent to A1 Organics.

What can I do to prevent pests and bad odors? 

Be sure to put your food and yard waste in either a compostable bag (made of plant material) or paper bag before placing it in your compost cart. Compostable bags are available at local businesses and paper bags are available at most grocery stores. You can also freeze your compostable food items and put them in the cart on your pick up date.