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Does a Compost Bin Need Sun or Heat?

Composting is one of today’s most effective ways of turning garbage into gold. One of the many questions that people who are looking to start composting ask is what their compost bin requires to be most effective for use.

So, does a compost bin need sun or heat? Heat is crucial to speed up the processes that converts the organic matter in your compost pile into humus, and what better way to provide the heat than the sun? It is free, cost-effective, and reduces your carbon footprint.

However, you will require steps to keep it cold as the full sun can cause the closed system to overheat; that is, assuming that you keep it closed for the smell and pests to remain in there. You may be tempted to place the bin in the shade as well to protect it from the sheer heat of the sun and other elements such as rain, wind, and snow, but by so doing, you will lose the speedy decomposition that the sun’s heat provides. 

Where Should You Place Your Compost Bin?

Here are some pointers to help you decide the most optimal place for your compost bin:


Temperature is a key factor in determining the speed and efficiency of decay, with the rate increasing with an increase in temperature. This simply means that decomposition will occur in the shade, but not as well as it would in the sun. 

If you live in a place that is more prone to extreme weather conditions and placing the bin in the shade is more actionable, consider purchasing a black bin. While these bins are usually designed to close tight to protect against the rain, snow and wind may be more serious threats. Black bins are able to absorb heat more effectively regardless of their position. 

In the winter, you are advised to place your compost bin in the shade. If you live in a hot region, placing the bin in the shade is also advised as too much heat will kill the microbes, dry out essential moisture, or even start a fire. Compost bins are made of heavy-duty plastic, but under excessive strain caused by persistent exposure to the sun can cause your bin to deform or warp, making it difficult to seal it securely.

Beneficial microbes require higher temperatures to survive and break down the organic materials in your bin; thus, you will still need a high temperature in the sun’s absence. To raise the temperature within the bin, you can add some nitrogen-rich components such as manure and seaweed. This, plus regularly turning the barrel to incorporate more air, will increase the rate of decomposition.

Moisture level

The sun is known to dry out compost piles inside bins, and you can tell if your pile is too dry by its appearance. It is time to move your bin to a place with partial sunlight if it looks more like dust rather than earth. You can also squeeze a sample from the pile; if it comes apart and does not release any water, then it is too dry. Inadequate water will slow down the rate of decomposition as the microbes require water to function. 

In addition to moving your bin to a place with partial sunlight, you can water the pile evenly to moisten it and unload some of the top layers to avail water to the lower ones. You can also add components rich in carbon, such as fresh grass or vegetable remains.

On the other hand, if your pile is in the shade, your compost may be too wet, which affects the decomposition process. You can tell that your pile is too wet by looking out for the smell of ammonia or the presence of matted piles. The excess water is depriving the aerobic microbes of the oxygen they need to keep working. 

You can fix this by aerating your compost. To aerate, you can spin the barrel, use a pitchfork to turn the material, or add additional brown material like shredded paper, leaves, or newspaper to absorb the additional wetness. You can also move the tumbler to a place with partial sunlight to evaporate some of the moisture.

Methods You Can Use to Heat up Your Compost

You are allowed to compost in the winter, when the sun is not as available as you would want it to be, or cannot place your bin in the sun due to the risk of overheating. Below are some few methods you can use to turn up the heat for faster decomposition and removal of excess water:

Get the size right

Compost piles require some mass to self-insulate and sustain the high temperatures needed by thermophilic bacteria to compost. The minimum size for a bin required for effective hot composting is 3x3x3 feet (one cubic yard by one cubic meter) up to 5x5x5 (1.5 cubic meters). With this size, turning will not be difficult and should make it easy for you to turn the material effectively, and will allow the organic material in the bin to self-insulate.

Copyright article owner is for this article. This post was first published on April 28, 2020.

Get rid of pathogens and weed seeds

The last thing you want is your beneficial microbes to have to compete with unhealthy pathogens and weeds for oxygen and moisture, not to mention the havoc they will wreak on your garden once you use the compost. Still, once the temperature hits 140 degrees, most plant pathogens and weed seeds will be killed.

Increase the volume of materials to decompose

The more the material available to decompose, the more heat the pile will generate. This additional material will provide more space and resources for beneficial bacteria and fungi to grow and consume. You can start off with a high volume of organic matter or topping off what you already have with more garbage. With higher volumes, creating hot compost will be easier.

Add more nitrogen-rich components

As mentioned earlier, nitrogen-rich components like coffee will increase the temperature inside the bin. This is because nitrogen is starting material for the proteins that the microbes need, which will, in turn, boost their level of activity. Distribute these components evenly throughout your pile for excellent results.

Keep moisture levels in check

Even dampness is a must-have for speedy decomposition. By dampness, you should look for wetness resembling that of a sponge that has been wrung. You can maintain this optimal level of moisture by placing brown materials like paper and leaves at the top of the pile.

Monitor your thermometer keenly

While temperature is key for optimal decomposition, there is a level of heat that will do more harm than good. Your pile is considered hot if your pile is between 130 and 140 degrees, above which the activity of beneficial bacteria will be inhibited. You can check your pile for heat by digging into its very core and feeling for warmth and watching out for steam. For a more accurate approach, a compost thermometer is the better option.

ReadyToDIY is the owner of this article. This post was published on April 28, 2020.

Boost the level of air in the bin

Air is important for aerobic bacteria to carry out their role, and you can aerate your bin by turning it. Avoid turning your pile too often as it will dry out. As you monitor your bin’s temperature, you will be able to identify spikes and falls in temperature, and you are advised to turn your pile only when the temperature falls. Aerating your pile once in a week is sufficient.