Compost kept in the sun will break down faster but will also dry out faster. Compost kept in the shade will stay moist for longer but will break down slower. Large compost bins made from timber can go in full sun as they will stay moist longer, keep small, black compost bins in the shade to keep them moist.
This article will explore if compost should be kept in the sun and the best place to put 8 different composting systems and types.
Should you keep compost in the sun?
Here is my easy guide to the type of compost system you are using at home and if it should be kept in the sun or shade.
|Black plastic compost bin (Small)||Part Shade|
|Black plastic compost bin (Large)||Sun or shade|
|Tumbler compost bins||Shade|
|Wooden compost bins||Sun|
|Compost piles||Sun or shade|
|Hot composting systems||Sun|
|Worm composting systems||Shade|
Small black plastic compost bins (small)
Smaller compost bins should be kept in part shade, particularly if they are black because they can heat up fast and dry out. They can overheat and kill off the good bacteria that are working to break down your compost. Worms will escape out the bottom of the bin to escape the heat and will stop breaking down your compost.
Small compost bins are great for small yards but keep them in the shade to keep them processing well. It is too easy to forget to keep them moist on a hot day.
Large plastic compost bins
Large plastic compost bin will stay moist for longer so you can keep them in the sun or shade. Once the bin is full of green and brown materials it will keep itself moist. Check it during the hot summer days if it is in the sun to make sure that it is not getting dry.
Tumbler Compost Bins
Tumbler compost bins are easier to keep in balance if they are kept in the shade. These bins are raised off of the ground and will heat up and dry out quicker. To make it easy for yourself keep it in the shade to make it easy for yourself and to slow down the rate that it dries out.
Tumbler compost bins will be fine in part shade, especially if it is getting morning sun and afternoon shade.
Wooden compost bins
Compost bins that are made from wood, homemade or made from pallets are fantastic in the sun. They can warm up in the sun but will not dry out as fast. Wooden compost bins that are larger than 4×4 feet will stay moist and break down fast.
Compost piles without any edges that are formed as a natural pile in your yard can be kept in the sun or the shade. Larger piles will break down fast and stay moist for longer. Worms and soil bacteria will travel up from the soil and find their way into the pile.
Compost piles that have direct contact with the ground soil will stay moist for longer. These are the easiest ways to start a compost system at home, just remember to keep the balance of 1:3 green material to brown and to stir it often.
Hot composting systems
Hot composting systems should be kept in the sun. The sun will aid in the heating process where bacteria and fungi break down the organic matter. Hot composting systems are the fastest way to make compost at home but they need a large volume to start and need to be turned often.
For more on hot composting, check out my article here: Why does a compost heap get hot? + the secret ingredient
Compost bags work well when they are kept in the shade. Because they hold a smaller amount of compost materials and dry out fast. I like to fill compost bags with fall leaves each spring. You can leave them in the bags throughout winter so they are ready to add to your garden beds in spring.
They are also a handy way to store brown materials ready to add to your worm bin or compost bin to help to dry it out.
Worm composting systems
Worm composting systems should be kept in the shade at all times. They can dry out quickly which can harm or even kill the worms. A worm farm kept in the shade will allow the worms to dig their way up and eat the organic matter on the surface of the worm farm. It will keep moist for longer and support them to break down food scraps fast.
Keeping compost in the sun – Pros
Here are the top benefits of keeping compost piles or bins in the sun.
1. Heats up quicker and breaks down faster
Compost kept in full sun will heat up quickly which will increase the rate that it breaks down. Warm composts will break down fast and quicky turn your organic matter into finished compost ready for the soil.
2. You can place the compost pile anywhere
Not worrying about the shade will mean that you can put your compost pile in more places. Whether this is in the corner of your yard, against a wire fence or at the back of your chickencoop it makes it easy to find somewhere to set it up.
For large compost piles or home-made bins made from wood, this means you can set them up where you please, let the sun help to heat the pile up and get compost fast.
Smaller bins will need some shade so consider placing them near or under a tree so they get protection from the afternoon sun.
Keeping compost in the sun – Cons
Here are a few cons of keeping compost in the sun.
1. Dries out faster
Compost in bins or piles will dry out faster in the sun. Larger piles will take longer to dry out but the surface at least can get crumbly and crusty. If your compost still needs to break down, turn it often and add extra water on hot days. A layer of straw mulch will also help to insulate it, like mulch and keep it moist for longer.
2. Attracts more flies
Compost bins in full sun that contain a lot of food scraps can attract flies quickly. Fruit and vegetable scraps will rot and smell quickly if they are uncovered in the sun and can attract more flies which can lay their eggs in your compost. While this does not cause harm it can be annoying having these flies around your yard.
When adding food scraps to your compost bin in the sun take some time to dig them in or cover them with some extra brown material like dry leaves, hay or straw. Keep the balance of 1:3 green material like food scraps to brown material like leaves and hay to make it less appealing to flies.
4. Small, black compost bins can heat up fast
Small, black compost bins made from plastic in full sun can heat up fast and dry out faster. It can kill of the bacteria and send the worms down to deeper soil. For small, plastic bins, part or full shade is best to stop them from drying out.
Should Compost be Kept in the Sun? | Summary
Compost can be kept in the sun if it is in large enough volume to keep moist on the hot, summer day. Large compost piles or those surrounded by timber will break down fast in the sun. Smaller compost bins made from recycled plastic that are black will work better if they are kept in the shade. Always keep your worm composting system in the shade to keep the worms moist and happy.
I am an accredited practicing dietitian, experienced gardener and a dedicated cook. I love writing and sharing my experience so you can learn from my successes and mistakes.