Friday, May 28, 2021

Composting Considerations

By Denyse Schrenker, Eagle County Extension

I have a confession: I used to put grass clippings, leaves and yard waste in the garbage. Why did I waste all those great sources of organic matter? Why?!? Because it was easy and that’s what we did growing up! While I have not convinced my parents to start a compost pile, I have at least convinced them to leave their grass clippings on the lawn - a step in the right direction. What’s with their aversion to composting? Although composting is a fantastic way to convert our yard waste and some kitchen scraps into a great soil amendment and keep organic material out of our landfills, it can seem like a daunting and complicated procedure that requires a degree in organic chemistry to get right.

Home composting can be a simple and easy process, and I promise no knowledge of organic chemistry is required. A quick internet search of home or backyard composting (don’t forget the :edu!) will give you a plethora of great resources on how to compost at home. Composting in Colorado is the same as anywhere else but there are a few considerations we need to give more attention.

Office compost pile

Dry air & low rainfall

The organisms that are decomposing the compost materials need water to live. When parts of your compost pile dry out those microorganisms die and decomposition slows or stops in those parts until water has been added and they have had time to rebuild their populations. Water your dry brown (carbon) layers when you add them to your pile and water the pile regularly.

Your compost pile should be damp but not soggy. If you have a compost bin that is made of wire, you may notice that you have a hard time keeping the exterior of the pile from drying out. You can line the bin with plastic, or cover the pile with plastic, a tarp, or cardboard to keep the pile from drying out. Bins made of wood, plastic, metal or brick/concrete blocks will keep the pile more evenly moist and not dry out as fast.

Even with bins made from these materials you may still want to cover the pile. If you cover the pile with a tarp or plastic, try to place the bin where it will be partly shaded during summer or uncover the pile on hot days. Temperatures exceeding 160℉ will cause the decomposing organisms to die. I highly recommend buying a compost thermometer so you can monitor the temperature of the pile. They are around $20 and widely available online or in hardware and garden supply stores.  

Cold winters

Our cold winters make it hard to keep backyard compost piles active during winter which extends the time it takes to reach a finished product. Do not turn your pile after November in the mountains, to retain heat and keep the process going as long as possible. In the spring turn the pile and mix in fresh materials to reactivate the process.

I also suggest removing your finished compost at the end of the summer/beginning of fall so you have an empty or nearly empty bin. You can add the finished compost to your garden in the fall or wait and add it in the spring. I like to add the finished compost in the fall but wait to incorporate it until the spring, that way it acts like a mulch covering any bare soil over winter. Add your fall yard waste to the empty bin and continue to add your food waste to that bin over winter. In the spring add a brown layer (carbon source) and mix the pile. Bins made out of a more insulating material such as wood will also help prevent heat loss and keep the pile active longer into winter. Larger piles will retain heat better and stay active longer as well.


We live in close contact with our wildlife neighbors, especially in the mountains. Animal pests create another composting challenge. Animal products such as meat, dairy, bones, egg yolks and fats can attract unwanted critters so do not add those materials to your compost. You might want to avoid adding peanut butter as it attracts animals as well. If you are having a hard time keeping rodents out of your wood compost bin you can line it with hardware cloth. Cover fresh kitchen scraps with a carbon layer or bury them in the pile. Covering the pile with plastic, a tarp, or cardboard will help keep animals out as well - be sure to secure the cover. You might even want to make a lid you can secure over your compost bin to keep larger animals out.    

Basic Compost Troubleshooting




Compost stinks like rotten eggs

Lack of air - either too wet or too compact

Turn the pile or fluff it well and make sure it is not soggy wet.

Compost stinks like ammonia

Too much nitrogen

Add carbon source; dried leaves/plant material, chipped woody material, sawdust, wood chips, hay/straw.

Materials will not decompose

Pile is too dry, too small, or particle size too large

Check if the pile is dry - water regularly and cover if outer inches of pile consistently dry. Add more material and mix in with old material. Shred/chip large materials. 

Pile is damp and smells sweet but will not heat up

Not enough nitrogen

Add nitrogen source & mix well: grass clippings, fresh plant material, coffee grounds/veggie kitchen scraps, bloodmeal, fertilizer, manure from herbivore. 

Pile is only damp and warm in the middle

Pile is too small

Add more material and mix in with the old material

***If you add manure as a nitrogen source it should be from plant eating animals and you need to let the compost cure for 6 months to reduce pathogens if you want to use it in a food garden. Pathogens may still be present even after the curing process so wash all fruits and vegetables thoroughly and follow safe food handling practices. 

Do not add:

Meat, dairy, bones, oils, fats, human or pet feces, plants treated with weed killers, diseased plants, weeds that have gone to seed, wood or charcoal ash, highly resinous wood & leaves (junipers, pine, spruce, arborvitae), large amounts of leaves high in tannins (oak, cottonwood)

For more information check out: 

Fact Sheet 7.212: Composting Yard Waste

PlantTalk Colorado 1613: Composting

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