Hot vs. Cold Compost: Which Is Right For Your Garden?

Save waste from landfills and start a composting pile today. It’ll allow you to morph your waste into free soil, saving you money when it’s time for planting. You help the environment and your wallet when you decide to start composting!

Compost isn’t difficult to make, but information online may confuse you as you see bins, tumblers, and all sorts of methods that cost money before you start. Truly, all you need to start a pile is a pitchfork, waste, and some space in the yard. 

The next decision to make is whether you want hot or cold pile. Both methods have benefits and drawbacks, and they take different amounts of time to finish. Let’s see how the materials you add, the work you put in, and how much time you have dictate what type you should make.

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The Short Answer

Hot compost decomposes quickly but requires more upfront labor than cold composting. It’s typically higher in nitrogen than carbon, since fleshy green parts decompose quicker than dry brown ones. Cold compost decomposes slowly but needs less maintenance and water.

The Long Answer

Whether you should make hot or cold compost depends on how much waste you have and what kind of mulch you’d like to create. Let’s break down what puts cold and hot composting apart from each other and which method is right for you!

Hot Compost is Quick

Hot piles decompose waste quickly, as they help the microbes and small creatures develop and reproduce. You can have ready compost to use in your garden anywhere from two to three weeks.

The key with hot composting is regular turning and watering. You’ll want to use your pitchfork to rotate your materials daily or every other day. Turning facilitates airflow, which increases how much oxygen is in the heap. Low oxygen creates anaerobic decomposition, which is smelly, slow, and attracts animals. Turn your materials daily to avoid it.

Water helps the microbes eat and reproduce. Aim to have it at 50% moisture—it’ll be moist but not soggy. Test the moisture level by grasping a clump in your hands. It should feel like a wrung-out sponge. If it’s too wet, you can turn it to encourage even moisture levels. 

Cold Compost is Easy

I love cold composting simply because it’s super easy to do! Start with the same ratio as hot compost, with 1:2 or 1:3 parts green to brown. You’ll still have to turn the material, but less often than with hot heaps. Aim to turn them in once or twice a month. This will keep anaerobic decomposition at bay and help rotate the waste so it decomposes evenly.

Although cold composting is easy, it’s also a long process. You won’t have ready soil for at least three to six months. So, how is it beneficial? Well, cold decomposition allows you to upcycle waste as you have it. You can continuously add biodegradable materials, turning and watering it as needed. 

With hot compost, you’ll want to start the heap and quit adding new waste. Fresh debris takes time to break down and slows down rapid decomposition. Recycle your waste year-round by maintaining one or two cold piles that accept debris readily. Harvest ready soil by lifting the top layers with a pitchfork—underneath should lie rich, crumbly dirt you can use as mulch, fertilizer, or in a potting soil mix.

Decomposition Rates Differ

Which method you choose depends on your needs and the debris you have. Wood contains plenty of carbon and takes longer to decompose than fleshy, green materials. Large chunks of wood slow down hot decomposition by soaking up nitrogen as they initially break down. This slows them significantly but is less impactful in cold ones.

A cold pile might be a better solution if you have lots of woody or papery waste throughout the year. You can make a hot pile for your garden and kitchen debris and a cold one for your woody materials. Be sure to balance both types equally, adding greens and browns in a ratio of 2:1 or 3:1.

One other way to speed up both methods is by using smaller pieces of debris. Use a mower, pruners, or a shovel to break up large chunks into smaller ones. Small particles allow more microbes and worms to eat them because they have more surface area that the critters can reach. 

Pathogens and Weed Seeds

Many sources say to leave diseased leaves and weeds out of your compost, but where else would you put them? Hot composting is an ideal solution, as high temperatures and beneficial microbes work in tandem to balance the pile. Kill most diseases and weeds by maintaining temperatures above 104°F (40°C) for five days, and ensure they exceed 131°F (55°C) for four hours during this time. Use a soil thermometer to measure your compost if you’re unsure.

If you have patience and time, cold composting is also an effective solution for destroying diseases. Seeds may persist and sprout when you spread it on the soil. Simply pull the weeds as they sprout and put them on top of the soil for free mulch—or, add them back into your compost!

Destroy diseases by letting your cold heap mature for a year or longer. Bacteria, fungi, and archaea work in tandem to suppress food and soil-borne pathogens as decomposition slows in old piles. Mature compost is also an anti-pathogen application, meaning you can add it to your raised beds to prevent future crop infections. Be sure to let cold compost mature for a year or longer for optimal disease-suppressing effects, and apply them as an amendment only once they look fully broken down.

Animal Disturbance

Squirrels, raccoons, and rats turn decomposing compost into a mess of scraps! If you have these critters living near you, opt for a hot pile and use walls to protect it. Wooden pallets work well as a quick solution; nail three together to form a U shape. Put your scraps inside the U, and place a fourth pallet on the end to seal up the bin. Wrap the pallets in chicken wire to further animal-proof them.

Tumblers are also animal-proof composting contraptions since they rest above ground in a sealed container. The downside? They don’t have access to soil microbes and worms. Fix this by placing a handful of dirt from the ground into the tumbler every time you add debris. 

Cold composting is the one method you’ll want to avoid if there are critters around you searching for rotting scraps. They’ll find them easily, and make a mess of your materials before they have the chance to decompose.

Final End Product

The last consideration to make is what you want your ready compost to do. Hot piles are best if you’re processing fleshy materials rich in nitrogen to turn them into usable forms that plants love. Heaps with lots of greens also tend to have more bacteria than fungi, which benefits plants.

Cold piles have nitrogen but tend to be richer in carbon than hot ones because of their lengthy decomposition process. Opt for cold composting if you grow lots of plants that prefer amendments with more carbon. Carbon-rich composts tend to have more fungi than bacteria.