Should compost pile be in sun or shade?

People who are new to composting often face the problem of finding the best spot for their composting bins. Some sources say you should put it in the sun, while other sources insist on putting it in the shade. Let’s solve this problem once and for all.

Should the compost pile be in the sun or shade? It is best to keep the composting bin in a partially shaded area. Sunlight can speed up the process, but it also dries up the mixture. On the other hand, Shade can keep the moisture levels intact, but it slows down the decomposition. 

However, there are many other aspects to this. The position of your composting bin also depends on which part of the world do you live in, the climate in your area, how much work you want to put in, how fast do you want the final product etc. We need to explore this a little more so you can have a better answer.

How much sunlight does a compost bin need?

Composting process requires warmth. The ideal temperature range for composting is 135°F to 160°F or 57°C to 71°C. It would help if you avoided the temperatures above 160°F or 71°C.

The sun surely helps to reach the desired temperature faster; however, composting can occur without sunlight. So, as long as you can get the temperature right, you can get by without sunlight. Though, several studies show that composting proceeds faster in sunlight.

Where Do You Live?

When it comes to placing your composting bin, there is no one size fits all approach. The answer varies based on where you live.

Hot Climate

If you live in a hot state like Florida, Louisiana or Texas, placing your pile is the sun may not be such a great idea. It can quickly overheat and kill the microbes and worms. I have even seen composting bins getting deformed by too much such. And those are not easy to close!

Most composting bins are black, so they absorb more heat. In peak summer months, they can get so ridiculously hot that you can’t even touch them. Here are a few tips

  • In hotter areas, you have to avoid direct sun. If you have a nice shaded area in your garden, it would be fantastic.
  • You can also change the colour of the composting bin, so it takes in less heat.
  • If you do want to keep it in the sun for faster output, make sure to perform regular temperature checks

Cold Climate

Living in a cold climate is no excuse to ditch composting. People living as far as Norway are successfully doing it. In colder climates, it’s hard to get the temperature of the pile to functional ranges. In most cases, it will take longer, and we have to accept that fact. In a cold climate, the sun becomes an invaluable ally for composting. You can keep your pile in the sun to help it reach a suitable temperature promptly. I would also like to add a few more pointers.

  • Adding more greens or nitrogen can heat the pile quicker.
  • The black colour especially comes in handy under cold temperatures.
  • Keep the moisture content low in the pile. It can turn anaerobic and get smelly.
  • If you live somewhere too cold, you should explore the hot bins.

Green to brown ratio

If you are into composting, you must be well aware of greens and browns. Greens comprise things like fruits and vegetables, which help in increasing the nitrogen content of the pile. Nitrogen is needed for microbe reproduction, and it helps in heating the pile. But greens are high in water content and can make pile wetter.

On the other hand, browns are your drier materials like sawdust and paper, which adds carbon to the pile. Carbon provides the required energy to the microbes. Browns are dry and absorb the excess water from the pile.

The required ration of browns to greens is 3 or 4:1. But now, you must be wondering how it affects your decision to place your composting bin in the sun or shade.

Well, you need to look at your availability of greens and browns. If you add more greens, your pile will have more moisture. You can balance it out by either keeping it in the sun or adding more browns. If you don’t want to add more browns, then you should move towards the light!

On the other hand, if you have more browns, then your mixture will be drier. You can rectify this by adding water, but if you keep it in the sunlight, you will have to add water to compensate for evaporation continuously. If the pile becomes dry, it will dehydrate the microbes hampering the process.

If you want to check the moisture levels, pick up a handful of the pile and squeeze it. If there is water coming out of it, it’s too wet; and if it’s too dry and fragmented, you need to add more water.

Shade Or Sun?

When it comes to a healthy composting pile, it’s all about the correct balance of temperature, moisture and materials(Greens and Browns). Placing the pile in the sun or shade can make it easier or harder to achieve stability. Let’s go through the pros and cons of both sun and shade

Placing the pile in the Sunlight

Pros Cons
The decomposition is much faster. The pile loses moisture much faster.
Its easier to reach the ideal temperature (Especially in cold areas) In warmer areas, the pile can get overheated quickly 
The overall quality of compost is higher. The compost needs more supervision.
Fewer browns (Dried materials like cardboards, straws etc.) are required. More greens (vegetable peels, fruit peels etc) may be needed to balance water

Placing the pile in the Shade

Pros  Cons
The pile retains most of the water.   Composting takes a longer time to finish.
  It is preferred in hotter climates to avoid higher temperatures in a pile.  The compost can remain below optimum temperature (Especially in colder areas)
The composting bin requires lesser management. The quality may not be as good ( But in most cases, the output is almost similar)
Lesser greens are needed (But you have to watch out for nitrogen content as it is needed to heat the pile, especially in the absence of the sun) More browns are needed to reduce water content( Browns are dry and absorb moisture)

Final Thoughts

It doesn’t matter if you keep your pile in the sun or shade as long as you can maintain the right temperature and moisture. Based on your location, you can use both sun and shade to your advantage and make your life easier. But for most of us living in places without extreme hot or cold, the best location to place composting bin is a partially shaded area. That way you can get benefits of both sun and shade at the same time!

Sources

  • https://www.researchgate.net/figure/Ambient-temperature-and-temperature-in-compost-during-direct-sunlight-heating-Fig-3_fig3_300419165
  • https://www.epa.gov/sustainable-management-food/types-composting-and-understanding-process
  • https://agritech.tnau.ac.in/org_farm/orgfarm_faq%27s_compost.html
  • http://compost.css.cornell.edu/physics.html
  • https://agrilifeextension.tamu.edu/library/gardening/composting/
  • https://extension.uga.edu/publications/detail.html?number=C816&title=Composting%20and%20Mulching

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