Why is Your Compost Not Heating Up? (7 Reasons)

Composting is now one of the most accessible and most acceptable methods of disposing biodegradable household waste. It’s a plus for farmers because we can eat healthily, compost our leftovers, and reserve their nutrients for our crops. Because there are no special skills required, you can start a compost pile right in your yard!

Although many composting methods exist, modern farmers lean towards compost tumblers because of their more versatile features. They keep rodents and vermin out of your compost, prevent the potent composting odor from escaping, and accelerate the composting process.

If you’ve decided to invest in a compost tumbler, your first few experiences will vary. Some will be just as you’ve predicted, while confusions may also arise. For instance, it’s relatively common for a newbie’s compost not to heat up, and this article will explain why. We’ll also provide a few tips on heating your compost tumbler. Dive in!

7 Reasons Why Your Compost is Not Heating Up

Regardless of your composting method, compost only thrives where there’s a balanced supply of oxygen, moisture, heat, and bacteria. The materials you’re composting also matter, alongside the proportion adopted.

If your compost isn’t heating up, it could be because of the size of the compost pile, the materials you’re using, access to heat, among others.

Your compost should heat up and decompose at an accelerated rate given all the right conditions. But when things don’t go as planned, the following reasons may explain the cause:

1. The materials are too large

Fresh leaves and branches are great additions to your compost. They also supply nutrients, and since they break down, their organic matter remains will improve the quality of the soil.

We’re afraid it’ll take longer for decomposition to occur if you’ve included these materials without shredding them. Even for smaller materials, the composting process will significantly speed up when there’s a smaller surface area to colonize.

2. A high water content

A high-water content can also interfere with the heating condition in the compost tumbler. If the materials are too wet, it keeps oxygen out. If there’s insufficient aeration, the bacteria responsible for decomposition won’t come alive, thereby impeding the process that generates and controls the heat in the compost.

Aside from the apparent lack of heat, an unpleasant odor indicates that your compost contains too much water. If the materials look swampy, reduce the water content without delay.

3. Insufficient water

Proper composting requires a proportionate blend of dry to wet organic matter. If it looks too dry, it’s because there aren’t enough greens. Insufficient water in the compost will naturally delay composting. So, add more vegetable waste, tea, and coffee grounds, to name a few.

4. Too shady or too windy

It’s a no-brainer that leaving your compost tumbler exposed on a windy day will suppress the heat that would otherwise build up within the mixture. Some tumblers have thin walls that aren’t insulated, making it even easier for the wind to blow away any heat.

Your compost will also certainly fail to heat up when a shade obstructs substantial access to sunlight.

In this case, we recommend creating an appropriately sunny shelter and repositioning the tumbler.

5. You’re using old organic matter

If the organic matter in your compost tumbler is too old, it becomes incapable of sustaining the bacteria required for decomposition. Sometimes, deterioration also results in an imbalanced proportion of browns to greens.

6. You turn the tumbler frequently

Turning the tumbler once weekly is a reliable method of increasing the composting rate. Microbes create a delicate network when breaking down organic matter, and if you disrupt it too often, it impedes biodegradation.

Fungi and bacteria require a temperature between 120° to 160°F and opening your compost tumbler too often can cause that heat escape.

7. You reside in a cold clime

This is an apparent reason – if you live in a cold clime, your compost won’t heat up if you expose it to the harsh weather. You can buy a compost accelerator which you can use once monthly. It increases the composting rate regardless of the limited access to heat.

Requirements for a Hot Compost Pile

Generally, household waste is welcome, but only if it breaks down fast and is untreated. Examples of the materials that make great additions to your hot compost pile include vegetable matter, tea and coffee grounds, leftover foods, backyard clippings, wood shavings, among others.

However, the sensitivity of the materials in a compost pile and what they’ll be used for disqualifies some household items from being used as compost mix.

For instance, items that exude a potent smell are terrible for a compost bin because they can attract vermin. These destructive creatures can trace the scent of rotten meat, fish, bones, dairy products, and left-over kitchen grease.

Now that you know the materials for a hot compost pile, here are the requirements:

1. Turn the pile

Sometimes, your compost pile only requires a good turn to activate the heat. If aeration is insufficient, it can impede the activities of microbes in your compost pile. When they cannot access ample oxygen, they suffocate and take their heat with them.

So, to avoid leaving your compost pile in a laborious condition, turn it now and then.

2. Increase your nitrogen content

More nitrogen can increase the heat in your compost pile. Greens are suppliers of this substance, so when your compost pile looks dry, you can add more greens or moisture to reactivate the chemical reactions that generate internal heat.

It’s best to create a proportional measurement for your compost materials. You should choose what works best for you, even if it’s contrary to popular practice.

Bone meal, rear, corn gluten, among others, are excellent sources of nitrogen. They’re also a great substitute when you don’t want more green waste in your compost mix.

3. Monitor the moisture content

The moisture content for your compost pile also significantly affects the heating up process. The ideal water content should be comparable with a damp sponge, texture-wise. It won’t crumble when you take a handful either, and neither will water come out when you squeeze it.

If the pile is too wet, you can fluff it with a pitchfork to aerate it, leave it in the sun for a while, or add some brown matter.

4. Increase the size of the pile

In hot composting, a wider surface area means more room for bacteria to colonize. So, providing ample space for them to grow will improve the heat production in your compost mix.

Tips on Heating Up Compost Tumbler

There are many reasons why your compost isn’t heating up. We’ve identified some of them, so it’s time to explore viable solutions:

1. Ensure there’s an adequate supply of moisture

Adequate moisture is vital for decomposition. You can adopt an appropriate brown to green ratio to ensure proper hydration. So, if your compost appears dry, add more greens.

You can also increase the moisture content by adding some rainwater. You can also use tap water, but you must be mindful because it’s loaded with chlorine and chemicals that can destroy the microbes in your compost.

Moreover, leaving the water exposed through the night will undoubtedly reduce the potency of those substances so that you can use tap water from a day before.

2. Reduce excess water

If there’s too much water in the compost mixture, it prevents the compost tumbler from heating up. It should look wet, not soggy.

So, if you believe the mix contains too much water, you can spread the soggy area on a newspaper until the excess moisture evaporates.

Alternatively, you can introduce more browns to even the dominance of greens.

3. Add enough material to your tumbler

If your compost tumbler is half full, it may not reach its full heating capacity. The fuller the bin is, the faster the decomposition, so increase the quantity of your mix by sticking to your usual ratio of greens to browns.

4. Avoid composting old materials

Composting old materials is pointless because the bacteria they contain are barely strong enough to participate in biodegradation. Since they’re not suitable for composting, you can replace them with newer materials.

5. Shred your larger pieces

Always remember to shred large materials before putting them in the compost tumbler. Doing so simplifies the job for microbes, and when all the other requirements fall into place, decomposition will occur faster.

Smaller pieces also ensure adequate circulation of air in the compost tumbler.

6. It needs the right temperature

The compost pile temperature is critical because it determines how fast the mixture will break down. You mustn’t expose it to too much direct sunlight, but don’t keep it in an area that’s too shady either.

If there’s too much heat, say above 160°F, it kills the helpful microbes. So, regulate the temperature when you believe it’s too hot or shady.

7. Get some compost accelerator

Compost accelerator is an excellent buy for farmers living in cold climes or green thumbs who want to increase the decomposition rate. They’re concentrated levels of fungi and bacteria injected into compost to activate decomposition.

How Long Does it Take For Compost to Heat Up?

Compost mix fends off diseases, retains soil moisture, and reduces the need for inorganic fertilizers. It’s not only an excellent waste disposal method but also massively beneficial to farmers. 

Heating up is vital to set the decomposition process into action. So, how long does it take for compost to heat up? Well, the straight answer is that it varies.

First, the other factors necessary for biodegradation must be in an adequate supply. They include water, oxygen, and microbes. A chemical reaction results when these factors are in proximity, causing internal heating.

At a temperature of 120°F, it will take your compost pile one week to a month to heat up. However, many factors also contribute to the decomposition process. They include:

1. The size of the compost

The size of the compost pile can either slow the composting process or accelerate it. If you use a larger bin, your mix will break down much faster because there’s ample space for heat retention.

Smaller bins also come in handy; placing them in direct but protected sunlight will hasten the composting process.

2. The type of ingredients used

In composting, the organic matter is created by a fusion of carbon and nitrogen. Brown materials like cardboard facilitate carbon production, while green materials like vegetable waste provide nitrogen.

If you want it to heat up fast, it must contain a balance of green and brown materials.

3. The temperature

You cannot rely on the size of your compost bin alone for heat retention – sunlight or an artificial heat source will accelerate the composting process, especially when it ranges between 120 to 160°F.


If your compost isn’t heating up, it means you’ve missed a step. You can use this piece to retrace your composting processes to discover what went wrong.

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About Rinkesh

A true environmentalist by heart ❤️. Founded Conserve Energy Future with the sole motto of providing helpful information related to our rapidly depleting environment. Unless you strongly believe in Elon Musk‘s idea of making Mars as another habitable planet, do remember that there really is no 'Planet B' in this whole universe.