Yes, you should cover your compost pile for two main reasons. A compost pile that has no cover can become dried-out if you’re having a hot period of weather. Covering a compost pile will keep it shaded and help to retain moisture. Constant rain will wash out some of the nutrients of a compost pile that isn’t covered.

Also: Should a compost bin be in sun or shade?

Can you compost hand warmers?

The cover can be close fitting to the surface of the compost pile but be aware that the material that you use as a cover may absorb heat from the sun. This heat will transfer from the cover to the material on the top of the compost pile. While heat can play a part in making compost, the heat-source that works best is the heat that’s generated from within the compost pile.

Placing a cover of any type on a compost pile will serve to retain some of the heat that the compost pile generates. It’s important to allow air movement to happen underneath a cover. Do what you can to leave a gap between the cover and the top of the compost pile.

The second main reason for covering a compost pile is to stop the excessive moisture from rain. In some parts of the world there may be considerable quantities of rain. A good cover is needed to stop rain-water from soaking into the compost and flushing out the valuable nutrients that we want to keep in the compost pile.

Other reasons for covering a compost pile

Keeping a compost pile covered can help to reduce any smells that may be emerging. A cover won’t eliminate smells completely. If you have a problem with a compost pile that smells really badly, then the procedure that you’re using probably needs reviewing. Check [Smelly compost].

Placing a cover on a compost pile will deter the unwanted attention of pests. These include everything that sees your compost pile as a restaurant. There will be rodents, birds and flies. All of these and possibly more, will take an interest in your compost pile.

It is possible to deter invaders by covering compost but if they are determined enough to get in, they will.

What should you cover a compost pile with?

You can cover a compost pile with any old material that you can get your hands on. The favourite material is plastic sheeting. Some say that you should make holes in plastic to allow air to get in. I’ve never found this necessary. You will never get such a good enough seal from a plastic sheet to prevent air from getting to your compost.

Some people use a piece of old carpet as a cover on a compost pile. You should bare in mind that some carpet material will rot. This won’t be a problem as it will become part of the compost unless you’re using synthetic carpet which will behave like a plastic sheet.

Depending on how you go about making compost, you could cover a compost pile using a small sheet of plywood. It would need to be treated wood, to give it some ‘life’.

Plywood could be used if you’re constructing a compost pile that’s enclosed by wooden pallets that are tied together with string. This type of cover would need to be weighted down because the wind always likes to make a nonsense of sheets of plywood that aren’t secured.

Other ways to cover a compost pile

If you’re covering a compost pile to stop predators from getting at a recently added batch of waste, the best thing you can do is to try to bury it in the compost. Anything that sits on the surface of a compost pile, will be an obvious attraction.

Fresh kitchen waste usually carries a food element. It’s also usually high-nitrate material. The most effective way to cover this is to use a high-carbon material. This will not only cover the compost but help to balance the nitrate content.

The type of material you can use for this can vary according to what’s available at the time. In the Summer, there may be an abundance of lawn clippings. Place a layer of about 2 – 3 inches on top of fresh waste as a cover. This will put everything else out of sight and cover it enough to reduce the smell.

Other carbon based material will include shredded paper or cardboard and dead leaves. 2-3 inches of this should provide enough of a cover on the compost pile. Before covering kitchen waste with anything, it will be worth adding some hydrated white lime. Sprinkle enough to lightly cover the surface of the waste, then cover over with whatever carbon based material that you have.

Should a compost bin be in sun or shade?

Too much of one thing and not enough of another, is usually the reason why a plan hasn’t worked. If a compost bin is subjected to too much heat from the sun, there may be problems. If a compost bin is kept in the shade, it may take longer to make compost.

So,should a compost bin be in sun or shade? A compost bin can be in the sun or shade. A compost bin in the sun will absorb heat which will affect the compost that’s against the outside surface facing the sun but the benefits are marginal. A compost bin that’s made of plastic will last longer if you keep it away from the sun and place it somewhere in the shade.

Full compost bins will stay cooler

There is concern among some that a compost bin needs to be in the shade to avoid heat distortion from the sun’s heat. This is probably true in the hottest parts of the world but when a compost bin is full or just half full of compost, there is enough of a cooling mass to draw the heat away.

Plastic compost bins need to be in the shade

Compost bins made from plastic are potentially susceptible to the sun’s rays of ultraviolet light. This can be damaging in a number of ways. It’s the main reason why we need to shade our skin from the sun. Ultraviolet light from the sun, is what gives us a sun-tan.

The long-term effect of ultraviolet light on plastic, is to break it down completely. If there is one single reason for shading a compost bin from the sun, then, this will be it. However, if the plastic that forms your compost bin has been made using, what’s known as UV stabilised plastic, this will extend the life of the bin quite considerably.

There appears to be no effect on a plastic compost bin, that’s made from UV stabilised plastic, whether it’s shaded from the sun or not. Ultraviolet light from the sun, will find its way into shaded areas, although to a lesser degree.

You will notice if your plastic compost bin hasn’t been made from UV stabilised plastic. It will probably survive, whether shaded or in the full sun, for a year or two, possibly longer. Then you will see lots of tiny cracks appear in the plastic material.

When you see this, you may be tempted to empty the compost bin and move it to a more shaded place. It’s usually better not to do this. The sun has done enough damage to weaken the entire bin. If you try to move it at all, you risk breaking it. It may shatter into pieces. It’s usually better to just leave it where it is, regardless of whether it’s in the sun or shade.

It’s surprising how long a plastic compost bin will last, even if it’s been subjected to weakening from the effects of the sun. It may look a bit rough but it can still be usable.

Compost doesn’t need heat from the sun

The general view is that compost needs to be hot. The heat that works for compost is heat that’s generated from within the compost in the compost bin. Heat that’s generated directly by the sun will have an effect but only on the compost that is pressed against the inside of the compost bin.

So, on the question of whether a compost bin should be in the sun or shade, being in the sun will provide some good effect that will help the compost but this effect will be minimal. It won’t affect the contents of the compost bin as a whole.

By the same token, if a compost bin is placed in a shaded place, away from the sun, the lower temperature may affect the composting performance but it will only affect the compost that’s touching the insides of the compost bin.

Some people seem to have the idea that if a compost bin is away from any shade and in the full glare of the sun, that there is a risk of the compost becoming so hot that it may catch fire.

It’s possible for the sun’s heat to dry out the contents of a compost bin to the point where it could burn. A fire is unlikely to happen just as a result of a compost bin being in the sun. There would have to be a spark from something that’s more local for such dry material to burn. In hot parts of the world, the contents of a compost bin will dry enough to burn, even if the bin is in the shade.

Hot compost is no good to worms

Another consideration that not many people mention is the effect that heat will have on worms. The sun will warm the outer regions of the compost that touches the bin. It will likely become so hot that the worms will migrate away from this area. It won’t be a problem to them. They will have enough cooler mass available to them.

If you know that there are likely to be prolonged periods of hot sun, you should place the compost bin in a shaded place before you start filling it. Constant heating may pose a challenge to the worms; they can only take so much.

Does a compost tumbler need shade?

A compost tumbler needs the same attention and consideration as a compost bin.

Most compost tumblers are mounted on stands and therefore, are unlikely to have worms in them unless you place them in the compost. So you won’t need to shade a compost tumbler from the sun for the benefit of worms.

It’s generally better to place a compost tumbler in the shade because a tumbler is likely to hold less material than a static bin. The heat from direct sun will risk drying out this smaller volume. It’s also better to do the work of turning the tumbler in a place where it’s more shaded.

Do compost bins need air holes?

Most people know that for anything to rot it will need air. Nothing will turn into compost if it’s sealed in. Where there is no air we get the opposite of decomposition, we get preservation, which we don’t want. Some people concern themselves about getting enough air into their compost bins.

They look at their electric drills and ask themselves: Do my compost bins need air holes?

Compost bins do need air holes. Air is needed for compost to go through aerobic digestion. Having plenty of holes in compost bins will ensure that there’s enough air movement. Holes in a compost bin don’t need to be big. Small holes will let in enough air without allowing compost to fall out.

You don’t need your compost bins to look like the top of a pepper pot.

The amount of air needed to turn organic waste into compost is quite small. The compost bins that are made for the purpose will be designed to allow enough air in for compost to form from any organic waste. It may look as though there aren’t enough air holes in a bin but air will get in where the lid fits.

A loose-fitting lid can often be enough to allow in enough air. Where compost bins have slider-doors at the base, these will be sufficiently loose to allow for movement. Air will be able to get in at this point. Lids and outlet doors don’t need to be tight-fitting.

Compost bins shouldn’t need extra air holes

There shouldn’t be any need to add extra air holes to purpose made compost bins. Unless you are making compost from organic materials that appear to need more air, basic compost bins can be left untouched.

Where you may need to make air holes is when you find a plastic container that’s been used for something else. These tend to be industrial containers and if you’re lucky, some of these can be of good quality and make really good compost bins. They’re often of such good quality that they can be air-tight and water-tight. To make a plastic container usable as a compost bin, it will generally need modifying.

It won’t be just air holes that you need to make. You will also need to make holes for drainage. Compost won’t form if it’s sitting in water.

To make air holes, use a drill, if you can. Don’t make them too big, you don’t want compost to fall out through holes in the side of a compost bin; ¼ of an inch for air holes should be big enough. Place them about 6 inches apart. It may take a bit of skill to arrange them in a tidy pattern.

If you don’t have a drill, the next best way to make air holes in a plastic compost bin is to use a screwdriver and hammer.

Holes for drainage need to be much bigger. Air will move in easier than water will drain away. It may be better if the container has no base at all, which could mean cutting away a big area of plastic.

If you’re using a compost tumbler, you shouldn’t need to make any air holes in it at all. Plastic compost tumblers are designed for the purpose of making compost. They will have air holes moulded into them and these will be enough to provide all the air that’s needed. The regular tumbling action that the compost should receive, will be enough activity to ensure that the compost has enough air.

A bonus question

Can you compost hand warmers?

Someone wanted to know about how to dispose of those air activated hand warmers. I don’t know much about hand warmers but, by all accounts, they‘re a ‘life saver’ for anyone spending much time outside in very cold weather. But can hand warmers be composted?

Hand warmers can be placed in the compost bin. There are no toxic chemicals in hand warmers. When hand warmers can no longer warm your hands, the minerals that they contain, can be released into soil through the composting process.

Hand warmers contain activated carbon, vermiculite, cellulose, salt and iron, there shouldn’t be a problem. These types of hand warmers generate heat when oxygen is introduced.

There doesn’t appear to be anything in these types of hand warmers that will be harmful to the soil or plants where the finished compost will be used.

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