It’s simple: Food Scraps and Yard & Plant Trimmings ONLY!
The City and County of Denver, along with other Front Range communities, are working with regional compost manufacturer A1 Organics to create a high-quality, clean finished compost product made from materials generated from City compost collections. The goal is to keep food scraps and yard & plant trimmings out of the landfill to prevent harmful methane emissions while creating a marketable finished compost. This soil amendment will help Colorado farms and landscapes build healthy soils that absorb carbon dioxide from the atmosphere, reduce water and chemical use, and grow nutritious foods.
The goal is clean, contamination-free compost, and we need your help.
Learn more about the changes below, and always check the Waste Directory for your recycling and compost questions.
Click the links below to download the updated guidelines in English or Español:
Q: What are the accepted items in Denver's Compost Carts.
Food Scraps: Baked goods, Bones, Bread, Cereal, Cheese, Coffee grounds, Dairy products, Eggs & eggshells, Fish, Fruits, Gravy & sauces, Meat, Nuts, Pasta, Peanut butter, Pizza, Poultry, Processed foods, Rice, Salads, Sandwiches, Spoiled or moldy food, Vegetables, and Leftovers
Yard Debris: Flowers, Grass clippings, Houseplants, Leaves, Plant trimmings, Small branches (no larger than 4 feet in length and 4 inches in diameter), and Weeds
Note about Bags: 3-gallon or smaller countertop CMA (Compost Manufacturers Alliance) approved compost bags (PDF, 1MB) are accepted. No other compostable or paper bags are accepted.
Brown Kraft Compostable Leaf Bags (30-40 gallons) are accepted during heavy yard waste seasons only, April-June and September-November, without tape or twine – just roll down and hand crimp!
No other compostable or paper bags are accepted.
Q: What are the new compost guidelines?
Compost Guidelines are simple! Two categories ONLY:
- Food Scraps: Produce, bread, bones, meat, cheese, eggshells, coffee grounds (no coffee filters or tea bags), moldy food, uneaten leftovers, rinds, peels, pits, etc.
- REMOVE ALL- produce decals, stickers, rubber bands, twist-ties and anything that is NOT food.
- Yard & Plant Trimmings: Leaves, twigs, small branches, flowers, weeds, grass and yard trimmings, etc.
NOTE: ONLY 3-gallon or smaller countertop CMA approved compost bags(PDF, 1MB) are accepted. No other compostable or paper bags are accepted. We recommend saving money by avoiding bags all together – keep your items loose in your compost cart!
Q: When will I receive my compost cart?
Beginning July, delivery of compost carts will be phased in by neighborhood every couple of months and will continue into 2024 as we get through the city. Gradually phasing in our weekly compost service will allow us to better educate and coordinate with residents, mitigate contamination, and allow our collection routes to grow with the service. At this time, no action is needed from residents and they'll continue to receive the Phased Service Roll-out Credit on their invoice until we deliver their green cart. We will reach out directly to residents within each neighborhood before their service begins with resources to help them prepare. Existing customers will not see any changes in their service. If you are a current compost customer or not filling up your trash cart on a weekly basis, you can downsize your cart. If you are not a current compost customer, we recommend waiting until you receive your compost cart before downsizing your trash cart so you can know what size you need. Residents can request smaller or larger carts at any time through their Denver Utilities Online account, Denvergov, or by calling 311. As compost service is phased in, residents are encouraged to utilize the Cherry Creek Recycling Drop-Off, which is open for all food scraps and yard trimmings accepted for compost collection.
Q: Which items are NO LONGER ACCEPTED in the compost?
If it isn’t food scraps or yard & plant trimmings, it doesn’t go in your curbside compost bin. Here are some common materials that are no longer allowed in the compost and should be put in the trash cart:
- Paper products: including tissues, paper towels and napkins, tissue paper, brightly colored paper, paper scraps and shredded paper, tea bags, and coffee filters (please continue to put coffee grounds into compost cart and trash the filter).
- Food-soiled or greasy pizza boxes: continue to compost leftover crusts, throw away the greasy half of the box and recycle the clean half)
- All compostable packaging and products: even those that are certified compostable, including cups, utensils, plates and takeout containers.
- Compostable bags: except 3-gallon or smaller CMA certified compost bags(PDF, 1MB).
- Paper Yard Waste Bags: Except during the Leafdrop event.
Q: I'm not sure what goes in which bin. Where do I look?
Check the Waste Directory!
Find what goes where, receive service alerts, and check upcoming schedule changes. Available in English and Spanish as a web browser or free app on the App Store and Google Play.
Q: Why are we seeing these changes to the compost guidelines? Why was this decision made and by whom?
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 to create a high-quality finished compost product from materials generated from municipal collections. When items like plastic, glass, metals, latex gloves, and masks are mistakenly placed into compost bins they ultimately end up in A1’s finished compost product. Food scraps and yard & plant trimmings make excellent compost, but contaminants like plastic, glass, and metals break down into sharp pieces and/or micro plastics that destroy the compost’s value, leaving A1 with a product they cannot sell because it does not meet their standards for quality, marketable compost for use by farmers and gardeners.
The Front Range community has one regional compost manufacturer, A1 Organics, located in Keenesburg, Colorado. A1 has notified all communities within the state that are using their services that they are receiving high levels of contamination in the compostables collected from businesses and residents (specifically plastic, glass, metal, and other non-compostable materials). As a result, A1 cannot distribute their finished compost product made from community collection programs. They are calling for a cleaner stream of organics (what you put into your compost cart) and are accepting food scraps and yard & plant trimmings only for the time being. Municipalities and haulers across the state are stepping up to let their customers know: Keep compost clean! Keep it simple with food scraps and yard & plant trimmings only. You can read A1’s notice to haulers and municipalities here.
Q: Why can’t I still compost “certified compostable” products and paper?
There are multiple reasons. For every certified compostable product (such as cutlery, tableware, cups, straws, and compostable bags) you might come across, there are several more “look-alikes” that mislead the public into thinking these items are compostable (using ambiguous terms like “biodegradable” or “plant based”) when in truth they often contain non-compostable plastics. Unfortunately, the volume of contamination A1 receives due to misleading labeling makes any packaging or serviceware items too costly to accept because of the challenge to distinguish and sort certified compostables from “look-alike” products that are not compostable.
Q: If compostable products and bags are a problem, why were they ever accepted?
While compostable bags and food serviceware do break down in the industrial compost process and can be useful vehicles for delivering valuable food scraps, the task of identifying what is legitimately compostable is impossible, even for experts, creating unmanageable amounts of contamination. Compostable serviceware products (such as plates, utensils, bowls, cups, and takeout containers) were not commonly used until relatively recently. As their popularity and participation in compost programs have grown, they have spurred a rush of “look-alike” and mis-represented products in the marketplace
Q: What do I do if I can’t put my compost in a bag?
Save money and go bag free! You don’t need to bag your organic materials – they can be loose in the green compost cart. In your indoor compost container or kitchen pail, go bag free and simply rinse out your container. If the cart is stinky, give it a quick rinse from the hose (do not include soap that will create residue in wastewater), swish it around in the cart, and pour the water directly onto your lawn or trees. If you have grass clippings or fallen leaves, you can line your curbside compost bin with a thin layer of grass or leaves to help absorb moisture.
Q: What kind of bags should I use?
If you choose to buy compostable bags to use in your kitchen pail or green carte, please make sure you purchase the right bags. All bags used for compostables must carry the official CMA (Compost Manufacturers Alliances) Logo. The CMA logo lets our drivers and processor know that products with this label have been tested to ensure that they will compost quickly, completely, and safely. Certified compostable bags may be purchased online and at some grocery stores. Learn what bags are accepted here(PDF, 1MB) .
Q: What will happen if contamination is found in a load of compost?
Compost loads will be rejected by A1 and sent to the landfill at the expense of the City, increasing methane emissions at the landfill. For this reason, our drivers will not be picking up any compost loads deemed too contaminated to pass inspection at A1.
The City will also be audit compost carts regularly to continue to educate residents on what goes in their carts.
Q: Can’t contamination be removed?
The organics recycling steam (aka compost) is not the same as the recycling stream. At a recycling plant, human sorters see contaminants like plastic bags and pull them off the sorting line by hand. Automatic equipment such as screens and optical sorters help separate materials. In comparison, by the time compostable materials arrive at a compost facility, they are already a gooey mess. Imagine pulling plastic stickers off of rotten banana peels, or even pulling plastic bags off of decaying material. A certain degree of contamination in sorted recycled products is allowable with recycling markets. Compost is not so lenient. Small pieces of plastic, glass, or aluminum will remain in the finished compost product. Farmers, gardeners, and other compost buyers need the clean, nutrient-dense food scraps and yard trimmings. But they don’t want to grow our food using compost contaminated with glass, plastic, and metals.
Q: I don’t contaminate my compost but people throw trash in my carts between collections. How can I keep my carts free from contamination between collections?
The best way to keep your carts free from contamination is to ensure that your carts are properly stored between collections. Review the cart storage and set-out guidelines here.
Q: Are other composters in other states and communities having the same challenge? What is their solution?
A1 is not the only compost manufacturer making these changes. A large percentage of commercial compost manufacturers have simplified their guidelines to include food scraps and yard & plant trimmings because of these contamination challenges, including programs in other early-adopter composting communities, such as Portland, Seattle, Vermont, and California. As the demand for quality compost by farmers and gardeners increases and more communities initiate compost programs to keep organic materials out of our landfills, compost processors are simplifying their compost stream to tackle contamination and ensure a quality finished product.
Q. What if I know I have certified compostable products? Can I still put them in the bin?
NO. Beginning April 1, 2023, A1 has notified Denver that the inclusion of paper, compostable products, and non-compostables will result in a rejection of the load and it will instead be sent to the landfill. Please do not include any paper (not even coffee filters or greasy pizza boxes) or compostable products, even if they are labeled as certified compostable.
Q: Are there things I can be doing to be an eco-friendly diner if I can't use compostable to-go containers?
- Know before you throw. Become a Zero Waste sorting pro. Check the Waste Directory to see if your to-go container is recyclable. Do not recycle “compostable” to-go containers.
- Use reusables whenever possible. The switch to reusable shopping bags has become the norm. Keep the reuse habit going—bring your reusable mug to a coffee shop, stash a reusable set of silverware and a napkin in your bag or car for easy access on-the-go, and bring your own reusable to-go containers for leftovers. Skip the stuff and say no to disposable items like plastic cutlery and condiment packets.
- Support reuse businesses. Have your to-go meal packed in DeliverZero reusable containers when ordering from participating restaurants. Reuse service companies are on the rise, with more companies no doubt coming online soon, so encourage your favorite restaurant to join a reuse program to help switch the default away from single-use disposables of any kind, regardless of whether they are recyclable, compostable or trash.
Q: Are these changes permanent?
That is to be determined. A1 is a private, for-profit company: the compostables they receive from businesses, restaurants, schools, institutions, and residents is only a very small portion of their business—and it is the most problematic portion because it has so many contaminants in it. A1 is not contracted or otherwise obligated to process the materials we have been generating. As community partners, A1 wants to work with haulers and municipalities along the Front Range to continue to accept material, but they need our help to ensure that it is substantially cleaner. At this time, there is no other compost processor in the Front Range region. A1 states that they are committed to finding the best solution for Colorado and will continue to work with our community to solve these contamination issues.
The goal of producing quality compost, and the health of the planet is best served by focusing on diverting food and yard waste while reducing the use of disposable single-use products (regardless of whether they are compostable or recyclable), by employing and prioritizing solutions around reducing and reusing first.
Q: What are the solutions to being able to take certified compostable products in the future? What is the vision for composting in our community moving forward?
Because compost is so essential for building healthy soils and as a critical climate solution, creating policies and infrastructure that support the success of compost are becoming key priorities on the state and municipal levels.
New policies are being introduced:
- A new Organics Waste Diversion bill will direct the Colorado Department of Public Health and Environment (CDPHE) to study and make recommendations about banning food and yard trimmings from the landfill and building the infrastructure needed to divert these materials into better uses like compost (this was one of CDPHE’s recommendations from the newly released Statewide Organics Management Plan).
- A Truth in Labeling bill would require all disposable food service products like cups, utensils and take-out containers to be certified compostable and labeled as such or not to contain any labeling that implies greenwashing, like “biodegradable,” “plant-based,” or “green.” This is to help reduce confusion and clean up the contamination from these non-compostable products in our compost stream.
New infrastructure is being researched and proposed:
- Stakeholders are looking at funding and implementing infrastructure solutions ranging from prescreening at compost transfer locations to building additional compost infrastructures at other locations.
- Stakeholders are working to create decentralized compost systems for on-farm composting, as well as smaller compost systems that could work for large generators like universities or small communities.
- Denver is working to support restaurants and other businesses with piloted reuse infrastructure to replace the use of compostables, recyclables, and disposables.
Q: What if I have questions about recycling or compost?
Q: Where can I learn more about my services, fees, and rebate?
Denver Composts is a weekly collection service for all food scraps, yard & plant trimmings. In January 2023, the city of Denver expanded solid waste services, and moved to a fee-based system for trash collections. As part of these changes, weekly recycling and compost collections are included at no additional fee. By adding weekly compost collection, Denver can reduce the amount of waste sent to the landfill by as much as 50 percent!
Beginning July, delivery of compost carts will be phased in by neighborhood every couple of months and will continue into 2024 as we get through the city. Gradually phasing in our weekly compost service will allow us to better educate and coordinate with residents, mitigate contamination, and allow our collection routes to grow with the service. At this time, no action is needed from residents and they'll continue to receive the Phased Service Roll-out Credit on their invoice until we deliver their green cart. We will reach out directly to residents within each neighborhood before their service begins with resources to help them prepare. Existing customers will not see any changes in their service. As compost service is phased in, residents are encouraged to utilize the Cherry Creek Recycling Drop-Off, which is open for all food scraps and yard trimmings accepted for compost collection.
Current Compost Customers
What are the benefits of composting?
- Composting keeps organic material out of landfills. In a landfill, climate warming gases, such as methane, are made as organics decay under anaerobic (without oxygen) conditions .
- Methane is 21 times more potent in its heat-trapping capabilities than carbon dioxide.; therefore, the benefits of composting organic material far outweigh the environmental “costs” of collecting, hauling and processing organic material with trucks and equipment that burn fuel.
- Organic material like food scraps and yard & plant trimmings make up about 50% of what Denver residents send to the landfill.
- The U .S. sent 25 million tons of food waste to landfills in 2005 — the greenhouse gas impact of composting this mass would be the equivalent of removing 7.8 million passenger cars from the road.
- Composting is nature’s way of recycling and returning valuable organic matter and nutrients to the soil to be used again. It can be used for gardens, lawns and even houseplants, to conserve moisture and add nutrients to help plants thrive.
- Incorporating compost into the soil can help to increase the soil's ability to retain moisture and reduce the need for fertilizers, herbicide or fungicide on farms, gardens and landscaping.
- Compost increases infiltration and permeability of heavy soils, thus reducing erosion and runoff.
- Compost can retain 100% of its weight in water and is an important component of gardening in a drought.
How do I manage odors or pests around my green compost cart?
Compostable material does have a smell. It’s the same stuff you put in your garbage, but now it’s just in a different container. Odor is often caused by too much moisture. You can minimize odor by:
- Ensuring you set your cart out for every collection.
- Draining as much liquid as possible from organic material.
- Keeping your cart clean.
- Burying your food waste underneath some yard debris.
- Wrapping food scraps with newspaper or placing in a paper bag before putting it in your cart.
- Freezing leftover meat and fish scraps and waiting to put them in your cart until your collection day.
- Waiting to clean out your refrigerator until the day before your collection day, rather than the day after.
The green composting cart is designed to be pest-resistant with thick plastic and a tight-fitting lid. Compost can attract fruit flies, so be sure to keep the lid closed. If you have problems with bugs and rodents around your trash now, you may experience some problems. If you do not currently have problems with pests, you should not experience any additional problems with your green cart.
It is the resident’s responsibility to clean their cart. A simple rinse with the hose every couple of weeks should keep the cart clean. A great idea for cleaning your green cart is to use a broom to reach the bottom.
How do I manage over-sized yard debris?
All branches or limbs placed in compost carts must be no longer than 4 feet in length, no larger than 4 inches in diameter, and no more than 50 pounds per piece.
Logs, stumps, and other larger yard debris are NOT accepted in the Denver Composts Program.
For information on dropping off larger yard debris materials visit Cherry Creek Recycling Drop-off.
How do I use my kitchen compost pail?
- Store your kitchen pail under or in the sink or on the counter to make it easy to access while preparing food or cleaning up after a meal. Find a new spot for your garbage pail so that you have to think before you throw something away - ask yourself, "Can this be composted?"
- Dump the contents of your kitchen pail into your green cart at least once a week.
- Drain as much liquids as possible from food before putting it in your kitchen pail.
- Rinse out your pail after you empty it or run it through the dishwasher on the top shelf to keep it clean and fresh. (WARNING: Running your pail on the bottom shelf of your dishwasher will cause the pail's lid to warp and not close properly.)
What kind of bags should I use?
Only 3-gallon or smaller CMA Certified Compostable bags are accepted in the green compost carts. No other brown paper or compostable bags are accepted.
- If you choose to buy compostable bags to use in your kitchen pail or green cart, please make sure you purchase the right bags. All bags used for compostables must carry the official CMA logo (Compost Manufacturers Alliances). The CMA logo lets our drivers and processor know that products with this label have been tested to ensure that they will compost quickly, completely, and safely. Certified compostable bags may be purchased online and at some grocery stores. Learn what bags are accepted here!
Never place any plastic bags in your compost cart.
- Plastic is a serious contaminant for composting. At the compost facility, all the compostable material is ground into fine pieces. When plastic is in the mix, we get small pieces of plastic that are hard to remove. Plastic is not compostable and will not break down in the composting process.
- Most supermarkets in Denver take back their own bags for recycling, so check with your local store to find out if they accept plastic bags for recycling. Consider using a reusable bag instead. Many stores will give you a 5 cent credit for each bag reused.
- Brown Kraft Compostable Leaf Bags (30-40 gallons) are accepted during heavy yard waste seasons only, April-June and September-November, without tape or twine – just roll down and hand crimp!
Should paper go in the compost or recycling?
- Paper products should not go in the green compost carts. Check the Waste Directory to see what paper products, like cardboard and office paper, should go in the recycling cart!
- Many paper products like tissues, napkins, paper towels, coffee filters, and pizza boxes can be composted in backyard compost. Learn more here!
Backyard composting vs. compost collection service?
- The organic material collected through the Denver Composts collection program is sent to a commercial composting facility in Keenesburg, Colorado that is run by A1 Organics. There, organic material is ground into fine pieces by an industrial grinder and then composted under controlled conditions.
- So materials that you wouldn't normally put in a backyard composting bin, such as meat, bones, and processed foods, can break down quickly in a commercial composting facility and contribute to making quality compost. After composting is complete A1 Organics performs a number of analytical tests on the compost, using an independent laboratory, to ensure the compost is a quality product before selling it.
- We encourage you to continue backyard composting if you're already doing so. These systems work great together! You can still compost lots of materials in your backyard while putting your meat, dairy, grains, and excess yard waste out for pick-up in your green compost cart.
Garbage disposal vs. composting?
There are no real environmental benefits to disposing of food waste through the wastewater system. In fact, it requires extra water usage to do so. Also, food waste can be the source of many plumbing problems. Disposing food waste through a garbage disposal increases the likelihood of clogs, especially if the food waste contains unsaturated fats, which solidify at room temperature and can build up inside pipes.
Placing food items in your green compost cart is a better alternative both environmentally, and for your home. Backyard composting is good too, just not for the meat or fat items.
What happens to compost after collection?
The organic material collected through the Denver Composts program is sent to a commercial composting facility in Keenesburg, Colorado that is run by
A1 Organics. There, organic material is ground into fine pieces by an industrial grinder and then composted under controlled conditions, so it can break down quickly and contribute to making quality compost. After composting is complete, A1 Organics performs a number of analytical tests on the compost, using an independent laboratory, to ensure the compost is a quality product before selling it.
Denver Recycles offers bagged and unbagged compost for sale back to Denver Residents at a discounted price each year at the Annual Mulch Giveaway & Compost Sale.
It is now easier than ever to close the compost loop and return finished compost made from the materials collected in Denver’s green compost carts back into your soil. Thanks to our partners at A1 Organics and Ace Hardware, bags of Denver’s Own EcoGro™ Compost are now available for purchase at neighborhood Ace Hardware stores.
The finished compost is also sold to farmers and other retailers. If you are interested in purchasing A1 Organics compost, it can be purchased retail from Pioneer Sand and Gravel locations or other local Class I and II Compost Suppliers.
Are businesses and apartments eligible for compost collection?
Denver Recycles, a program of the City & County of Denver Department of Transportation and Infrastructure, Solid Waste Management, is only authorized to provide services to residential homes of seven or fewer units and our own municipal facilities. Denver Recycles is not authorized to provide services to commercial properties such as businesses and apartment communities. Please visit our Apartment and Multi-family Recycling page for information on trash/recycle/compost at these buildings.
Ordering take-out? Here are some composting tips.
- Compost all of your food scraps!
- Trash the serviceware and paper products! These items are no longer accepted in Denver’s compost carts. Better yet, refuse these items when you can. Waste reduction is the best strategy and eliminates confusion!
- Make sure small plastics (i.e. condiment packets, straws) aren't accidentally thrown in your green cart.
- Go to the Skip the Stuff website for more information on how to help alleviate contamination when ordering out or eating in, go to the
- And remember, when in doubt, throw it out! Let's keep contamination out of our green carts.
It is now easier than ever to close the compost loop and return finished compost made from the materials collected in Denver’s green compost carts back into your soil. Thanks to our partners at A1 Organics and Ace Hardware, bags of Denver’s Own EcoGro™ Compost are now available for purchase at neighborhood Ace Hardware stores.
Composting food scraps and yard debris with the Denver Composts program is good for the environment, and good for Denver. Denver’s compost collection program is a way residents can keep organic material out of the landfill and help Denver meet its recycling and climate goals. In addition, closing the compost loop and putting finished compost back into Denver’s soil provides an even greater environmental benefit. When added to soil, compost:
- Improves soil structure and porosity, and encourages root growth
- Increases soil’s water holding capacity and moisture retention
- Enables soil to retain nutrients longer and makes nutrients more available to plants
- Provides beneficial microorganisms to the soil
Here’s what you need to know :
- Compost is a soil amendment that can be added to soil to provide benefits to plants and increase overall soil heath. Detailed use instructions are included below and on the back of each bag.
- Denver’s Own EcoGro Compost is an STA Certified compost product (meets the U.S. Composting Council’s Seal of Testing Assurance).
- Denver’s Own EcoGro Compost is exclusively available at Ace Hardware stores for $6.99 per bag.
- Denver’s Own EcoGro Compost contains materials from the Denver Composts collection program and materials from other similar municipal and commercial sources.
|Flowers and vegetable gardens
||Mix 1-2" into the first 6-8" of soil
||Apply 1-2" to planting area at start of growing season
||Mix 1-2" into the first 6-8" of soil
||Annually: apply a 1/4" layer before or after core aeration
|Trees and shrubs
||Use 1 part compost to 2-3 parts soil to backfill planting hole
||Apply 1-2" over soil surface of bed in the Spring or Fall (or both)
||Add up to 20% compost into potting mix
||Spread 2-3 tablespoons on the surface of the potting soil
Become a Denver Master Composter
The Denver Master Composter Training Program offers Denver residents a unique opportunity to both learn about composting and recycling topics, and to give back to the community through sharing this information with others. Through classroom seminars and hands-on experiences, Master Composter participants study a broad range of topics including the science behind the composting process, compost pile construction, resource conservation, and solid waste management. In return, Master Composters then share this newly acquired knowledge with the greater Denver community by teaching free “Learn to Compost” workshops and participating in outreach events at community gardens, schools and local farmers’ markets.
Organic material makes up nearly 50% of what Denver residents send to the landfill every year. These items can be composted, which is the controlled decomposition of organic materials by microorganisms. This process results in compost, a crumbly, earthy-smelling, nutrient-rich, soil-like material.
- Compost contains both carbon and nitrogen sources, which can be simplified as browns for carbon (e.g., leaves, straw, woody materials) and greens for nitrogen (e.g., grass and food scraps). Adequate sources of carbon and nitrogen are important for microorganism growth and energy.
- Organic materials are broken down through the activities and appetites of various invertebrates that will naturally appear in compost, such as mites, millipedes, beetles, sowbugs, earwigs, earthworms, slugs, and snails. These microorganisms need adequate moisture and oxygen to degrade the organic materials in the most efficient manner.
- Microbes in the pile create considerable heat and essentially "cook" the compost. Temperatures between 90 and 140 degrees Fahrenheit are common in properly maintained compost piles, but may not reach these levels in backyard compost piles. These high temperatures are necessary for rapid composting as well as for destroying weed seeds, insect larvae, and potentially harmful bacteria. When the compost is finished, it has a crumbly texture throughout the pile.
How to Get Started
- Choose a level area at least three feet square (3' by 3'). The area should receive only partial sun. The area can be fenced off, or you can use a pre-manufactured composting bin — see below for a list of bins and vendors for home composting
- Open the ground with a pitchfork or shovel approximately an inch or so under your pile area. This allows the soil microorganisms access to the food sources in your compost pile.
- Add an alternating mix of four-inch to six-inch layers of finely chopped high carbon and high nitrogen materials.
- To introduce friendly microorganisms to your pile, throw a handful or garden soil on top of the layers. Mix the carbon and nitrogen layers with a garden fork.
- Water the layers until they feel like a wrung-out sponge.
- Continue building your layers of carbon and nitrogen materials, remembering to throw a handful of soil on top of each layer. Mix each new carbon and nitrogen layer before watering.
- Direct sunlight slows the composting process, so cover the top of your pile with black plastic or straw. This also keeps the pile from drying out and slows the loss of soluble nutrients.
- Once a week, turn or stir your pile to provide air channels. A spading fork or commercial aerating tool can help with this.
- Keep your carbon and nitrogen layers finely chopped, add a little soil, build the pile a minimum of three feet high, maintain the moisture so it's like a wrung-out sponge, and turn it for air. In just two months, you will have your own brown gold compost!
If you supply the proper conditions (volume, surface area, moisture, air and variety of materials), you should have little difficulty maintaining your compost system. Occasionally, though, problems occur in any biological system. They usually can be dealt with fairly easily by following these tips:
- Odors - Odors can be caused by not supplying enough air to the mixture. Turning the pile can help. If the pile is too wet, turn the pile and add extra sources of coarse carbon, such as shredded twigs, alfalfa meal or straw. If there is too much high nitrogen material, add extra sources of coarse carbon as above.
- Pile doesn't heat - Typically, this is due to a lack of nitrogen material. Mix in high nitrogen sources, such as grass clippings or bloodmeal. The pile also may not be large enough to heat well. In this case, add more material until the pile is at least 3' x 3' x 3'.
- Center of pile is dry - If the pile is dry, it is not getting enough water. Remember to moisten the pile as you build it.
- Flies - Flies are attracted to decaying food scraps. Bury food scraps well within the compost pile. Food scraps may also be composted indoors using a ventilated worm box and redworms.
Compost is ready to use when it is dark and crumbly. You should not be able to recognize most of the materials, and it should smell like a damp forest floor.
- For vegetables, flowers and herbs - Fork it lightly into the soil several times during the growing season. It will conserve moisture, open up air channels in the soil, and slowly release nutrients for your plants.
- For trees and shrubs - After cultivating the soil at base of the plant, spread an inch or two of compost around the drip line. Leave the area surrounding the trunk free of compost to prevent mice from burrowing there in winter.
- For lawns - Spread aged compost thinly over newly aerated grass. Eventually, it will help loosen clay soild and allow a healthier, deeper root structure for grass plants. Deeper roots allow plants longer time periods between watering.
- For houseplants - Enrich potting soils by adding up to 20 percent finely screened compost. Make a good moisture retaining potting soil by mixing finely screened compost, sphagnum peat, and perlite.
Backyard Composting Bins and Vendors
A composting bin is a great way to control and accelerate your backyard composting efforts. You can build your own or buy a pre-made composting bin.
Local Compost Bin Vendors
- Ace Hardware-Alameda Station, 417 S. Broadway, Denver (303) 733-3200
- City Floral Greenhouse,1440 Kearney St., Denver (303) 399-1177
- Country Fair Garden Center, 2190 S. Colorado Blvd., Denver (303) 757-4949
- Echter’s Greenhouse and Gardens, 5150 Garrison St., Arvada (303) 424-7979
- Tagawa Florist and Garden Center, 7711 S. Parker Rd., Aurora (303) 690-4722
- McGuckin’s Hardware, 2525 Arapahoe Ave., Boulder (303) 443-1822
- Gaiam Living, 1215 Living Pearl Street, Boulder (303) 222-3300
Online Compost Bin Vendors
Resources for Building Composting Bins
There are many resources online to help you build several different types of backyard composting bins.
The information above is provided as a service to our residents. This listing of vendors does not imply an endorsement or approval by Denver Recycles or the City and County of Denver. All businesses listed are responsible for complying with all applicable local, state and federal laws.
Worm composting (or Vermicomposting) recruits red wiggler worms to convert our non-meat food scraps into nutrient-rich compost that can be used to improve the health of our yards, gardens and houseplants. See detailed information on How to start composting with worms (PDF).
Worm Compost Vendors
The information below is provided as a service to our residents. This listing of vendors does not imply an endorsement or approval by Denver Recycles or the City and County of Denver. All businesses listed are responsible for complying with all applicable local, state and federal laws.
What to Feed Red Wiggler Worms
In general, Red Wiggler Worms will consume fruits and vegetable scraps as well as the items in the list below.
- Fruit, leftover vegetable scraps and peelings
- Coffee grounds, tea leaves and tea bags
- Hair clippings (people and animals)
- Shredded paper such as newspaper and office paper (soak first)
- Crushed eggshells.
The greater the variety of material used, the better the casting (compost) will be.