Why Is Compost Tumbler Not Heating Up?

Composting is an environmentally friendly way of utilizing kitchen and garden waste. Moreover, it is a cheap and effective way of improving soil structure. For example, adding compost improves drainage if your garden soil is too muddy. If you have a big garden, you can dedicate a space for compost heap.

However, if you have a limited space in the backyard, purchasing a compost tumbler is a great option. You can compost all year round but the best time for composting is late summer or early winter. Composting can be cold and hot. If you just put the waste in a pile and wait, it’s cold composting.

To heat up compost pile you need high-nitrogen materials and increase the air exchange by turning the pile. So, the easiest and most efficient way is to use compost tumbler. If you built the compost correctly, it should heat up within 24 to 36 hours. However, if it has been a few weeks and compost tumbler is not heating up, something went wrong.

So, why is compost tumbler not heating up?

The most common reason why compost tumbler is not heating up is overloading with greens. Moreover, if you use leaves for browns, they take up to 6 months to breakdown, so switch to wood chips and shredded paper for the pile to heat up within 24 to 36 hours to the temperature of 141°F to 155°F.

Reason #1 – Compost pile is overloaded with greens

To get the pile to heat up you need to provide high nitrogen materials. It is vital to have right carbon to nitrogen ratio (browns to greens). So, the ratio by volume should be 2 measures of carbon (browns) to 1 measure of nitrogen (greens).

Green materials feed the microorganisms. When the balance of greens and browns is correct, bacteria and microorganisms function best to produce compost. Not sure what is green and what is brown? Here is a complete list down below.

Compost greens and browns list:

For example, to maintain 2:1 brown to green ration with every can of food scraps you put in a compost tumbler, you need to add two same size cans of browns. You can keep a bin of wood chips next to the compost tumbler, so it is easy to add them when you dump in food scraps.

Reason #2 – Used unshredded or fresh leaves

Leaves is a great source of brown material, however, if you throw leaves in a compost tumbler without grinding them up first, they can take up to 6 months to break down. Moreover, Magnolia or Oak leaves can take up to 2 years to decompose.

Also, if you just dump in leaves that are fresh off the plant, they take a long time to break down naturally. So, if leaves are still going to be a primary source of the brown material, just run them over with a lawn mower prior to throwing them in a compost tumbler. It increases the surface area of the leaves, so microorganisms can start feeding on them quicker.

Reason #3 – There is not enough nitrogen

It is as easy not to add enough high-nitrogen materials (greens) as overload on greens. If the compost is not getting hot, it can be low in nitrogen. To correct this, you just need to add more greens to the compost. You will know that you added too many greens such as grass clippings, if the compost becomes slimy and starts to smell.

The best mix is to combine kitchen waste and grass clippings with woody material as they tend to be wet and easily compacted, preventing air flow. Furthermore, mixing a variety of different sized materials creates air pockets. So, dump in twigs, stalks, straw and hay.

Reason #4 – You try to compost an old batch

If you are trying to decompose an old batch of compost that you had in a compost pile for some time, it might have lost its ability to heat up completely. Even with the new batch nothing happens if you messed up on the proportions. And now imagine that you are trying to decompose an old material where you don’t know what the proportions are.

Also, if the compost has been sitting in a pile for months and then you moved it to the tumbler, then there is a chance that it has decomposed and is not going to get hot and break down further. The compost is ready when its dark brown in color, the texture is crumbly and soil-like. It should smell like damp woodland.

Reason #5 – Compost is too wet or too dry

If the compost pile in a tumbler is too wet or too dry, it is not going to heat up. Too little air and too much water can lead to wet compost. To dry it, you need to take it out of the tumbler and spread it out on the newspapers. Not enough water and too much brown material can cause compost to dry out.

In this case you need to add water, so the texture of the compost is spongy. You can also add more greens or some fresh animal manure. Ideally, the mixture should be damp as wrung out sponge but not sopping wet. If you are scared to mess up the brown-green ration, you can add commercial activator or accelerator.

Compost starters and activators are products that contain high levels of nitrogen that is found in green waste. Some of them contain carbon that is found in woody brown waste. You need to use these activators if you don’t have enough browns and you want to break down grass clippings.

Compost starter can be a good solution for someone who lives in a cold climate and wants to speed up the heat up process. Just add two cups of Compost Starter to 55 gal tumbler and add some water to moisten the mix. Then turn the compost. Add activator every 4 to 6 weeks.

Happy composting!