Compost tumblers are environmentally friendly and an excellent way to recycle your garden and kitchen waste. They can be used all year round, don’t take up much space, and keep flies and other pests to a minimum.

Compost tumbler is not heating up because the organic material is either too dry or too wet. The beneficial microorganisms are unable to break down the material by aerobic process. So there is no heat generated. The lack of sufficient green and brown material may also cause this problem.

Compost tumblers need internal heat to do their job. If they don’t heat up, something is wrong. Permaculture uses the terms ‘greens’ and ‘browns’ to distinguish between the different elements of compost. Browns contribute carbon, while greens contribute nitrogen.

Why is compost tumbler not heating up?

To work well, a compost tumbler needs a good balance of nitrogen-rich, and carbon-rich organic material since the bacteria that break it down need both to flourish. They also need oxygen. The bacteria create the decomposition process that causes the tumbler to heat up.

Examples of greens are coffee grounds, eggshells, raw kitchen waste, fruit and vegetable scraps, lawn clippings, and manure from horses, chickens, cows, sheep, and rabbits. These are only one part of the equation and the smaller one at that.

The most probable reason for this is the ratio of brown to green material is off. If there is too much dry material (browns such as dried leaves, cardboard, etc) and not enough green material (food waste, manures etc) the tumbler won’t heat up. this can be rectified by adding more green material. If the bin is already moist but still not heating up coffee grounds is a good addition as well. Most times you can get it for free from a coffee shop and it can increase the temperature very quickly. – Nikita Legall, Gardener, Ah Grow!

The other side of the equation is browns. Examples are pine needles, untreated corrugated cardboard, straw, wood chips, dried leaves, shredded paper, sawdust, and cotton rags.

The general rule is that you need two units of browns for every unit of greens. With the correct ratio, the microorganisms inside your tumbler have the right balance of carbon and nitrogen to multiply and produce compost.

I asked fellow gardeners what they think is the reason a compost tumbler does not heat up. Below is the result of the survey that shows the different reasons.

1. The materials are not shredded enough

You added too many fresh, large leaves and branches to the compost mix. You should only use dried plant material and shred it first; otherwise, it takes too long to break down. Shredding all organic waste before adding it to the tumbler is recommended because it takes much longer to decompose if items are too big.

2. The materials are too wet

If the compost mixture is too wet, the oxygen in the air can’t permeate the mix, and the bacteria need oxygen to break it down. If water is dripping out of your tumbler or the mixture inside looks like a swamp, the problem is too much moisture. Another clue is the smell. Anaerobic bacteria that don’t need oxygen to live can generate an unpleasant odor.

3. The materials are too dry

Your material is too dry leading to compost not heating up. A fair bit of moisture is necessary for the decomposition process. If your compost looks dry, you may not have added enough greens. Too many browns and not enough greens mean the composting process will take much longer.

4. It is too shady or too windy for the materials

Is your tumbler standing in the shade or exposed to the wind? Move it to a sunny, protected spot. If your tumbler is not insulated and has thin walls, the heat can escape more quickly, especially if there is wind to blow it away.

Your compost tumbler might not be heating up for a variety of reasons. Probably the most common cause is thin walls. Thin walls means less insulation and an easier escape for heat. You might just want to buy a new compost tumbler that is insulated. – – Jeremy Yamaguchi, CEO, Lawn Love

5. You may be turning the tumbler too often

You are turning your tumbler too often. The bacteria and fungi that grow in compost form delicate networks that are disrupted by too much turning. Turning also causes heat to dissipate, and you won’t reach the ideal temperature. The temperatures at which the bacteria thrive are between one hundred and twenty and one hundred and sixty degrees Fahrenheit.

6. Organic material is too old

The organic material in your tumbler could be too old and may not be sufficient to sustain the necessary bacteria. Old organic material may have deteriorated to the point where you don’t have greens and browns in the correct ratio. It could also have already decomposed as much as it is going to.

7. The climate is too cold

You have not added a compost accelerator. Decomposition takes longer to start in cold climates, and an accelerator containing nitrogen and carbon can speed things up. If you live in a cold region, you may need to add a compost accelerator or activator every four to six weeks.

How do I heat up my compost tumbler?

Using the tips above, identify the problem as you need this information to apply the correct solution. Below are some ways you can heat up your tumbler.

1. Dry the materials out

If you think the mix is too wet, the best solution is to take it out, spread it around on newspaper or dry ground, and wait for some of the water to evaporate. You could also dry it out by adding more browns to absorb excess moisture. The mix should be wet but not soggy.

2. Add sufficient moisture

If your compost is too dry and you know there are sufficient greens, then add a little rainwater. Just don’t overdo it. Tap water often contains too much chlorine or other chemicals that can kill the bacteria in your compost.

If you use tap water, first let it stand overnight. If you are unsure if the ratio of browns to greens is correct, you can add a few more greens and see what happens.

The easiest way to heat your compost up is to take a shovel of dirt and add it to the compost. The dirt will have active bacteria that can act as a ‘seed’ to start new bacteria populations in your compost pile. You can also keep the tumbler in the sun, not in the shade. Bacteria in the compost tumbler will work faster when the compost is warm, not cold. Moving the composter to the sun will warm the compost, which will allow more bacteria to grow, and thus warm the compost even more. – Shelby DeVore, Gardener, Farminence

3. Make sure to provide the right temperature

Insulate your tumbler by covering it with a tarp or move it to an area that gets full sun if you have it in the shade. Just make sure to shield it from the wind. If your tumbler reaches interior temperatures of over one hundred and sixty degrees Fahrenheit, the bacteria will die off. To cool it down, move it into a shady spot or turn more frequently.

4. Fill your tumbler with sufficient material

Is your tumbler half empty? This could be why it isn’t heating up, so add more composting material in the correct ratios until it is full, or try using a smaller tumbler if you have one. Hot composting works well with around thirty cubic feet of organic material. If the volume of material is too small, it can’t retain the heat.

5. Add compost accelerator to the tumbler

Add a compost accelerator or activator if you live in a cold climate or just want to speed things up a little. These substances can be purchased at gardening stores or online. They contain concentrations of fungi and bacteria to kick start decomposition and maintain it. You can also try adding some molasses because the bacteria love the sweetness.

6. Shred or grind up large chunks in the material

Shredding and grinding the material into smaller pieces speeds up the process and helps to distribute oxygen more evenly throughout the mass. If you add lawn clippings, make sure they are not matted and clumped too tightly. Breaking the material into smaller pieces also allows more exposure to the bacteria.

7. Refresh the material

If the tumbler contents are old, remove them and add new material. If you think the material is lacking oxygen, turn it more often.

How long does it take for compost tumbler to heat up?

A compost tumbler should take between 36 and 48 to warm up. You can gauge whether it is heating up just by touching the outside of the tumbler with your hand, or you can use a compost thermometer.

How Do I Keep My Compost Tumbler Warm In The Winter?

To keep your compost tumbler warm in winter, cover it with a weatherproof tarp or move it to a sunny spot. If your winters are extreme, you can build a shelter for it or move it into a shed. Another solution is to lift it off the ground using a stand or pallets.

Many tumblers come with legs, so be sure to use them. Reduce the space available for cold air in the tumbler by keeping it as full as possible. The greater the volume of material in the tumbler, the better it will retain heat.

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