What can you put in your compost bin?

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For anyone who has never made compost before, the idea of storing up kitchen or garden waste, may at first, appear to be complicated. One of the first questions that you’re sure to ask will be what can you put in your compost bin?

Put in a balanced mixture of ‘greens’ and ‘browns’. Put in all waste food from the kitchen. This would include leftovers on plates, vegetable trimmings and fruit peel. Any food that’s gone off can also be put in the compost bin. Your compost bin is there to receive anything that will rot down.

Anything that is food to you will be food to something else including the microorganisms that convert green waste into compost. Selecting what you put in your compost bin is an easy process. Let’s look at it here.

All vegetable peelings

Hedge trimmings, weeds and lawn clippings

Getting a balance Paper and cardboard

Why should I make compost?

Does making compost generate CO2?

What do I do if my compost bin is full?

Does it make a difference if I use a bin or compost tumbler?

Waste from the kitchen

Any of the foods that you put in your fridge can be turned into compost. They all have the ability to go ‘bad’. Some items will surpass all expectations when it comes to putting on a mould display. This can happen to anyone. If something is left, with the best of intentions, at the back of the fridge and forgotten about, it will generate mould which can be described as a work of art.

If something’s gone off in the fridge

This isn’t something that you could proudly display but, because it’s already started the process of deteriorating, it can finish the process in a compost bin. When I say anything from the fridge I mean anything and that includes milk or yoghurt, if it’s gone thick and ‘off’. If you have cheese that started to change colour, then it can be put in the compost. Hard cheese can sometimes be rescued. You can trim off patches of mould, throw this in the compost bin and get away with it with the rest.

All vegetable peelings

When preparing vegetables you will have peelings and trimmings, usually in abundance. All of this can go in the compost. While you have your favourite vegetable peeling knife in your hand, cut the peel and trimmings into small pieces. If you do this it will take up less space wherever you store it before going out to the compost bin. It isn’t just vegetable peelings that can go in the compost bin, fruit leftovers can also be included. This covers everything from apple cores to the stalks left over from a bunch of grapes. Any citrus fruit peel can go in. For this I would add some hydrated lime to reduce the acidity. This is something that you should do when making compost, regardless of what you are putting in the bin. If you would like to know more about hydrated lime, we have another post that covers the subject. Check out ‘What does lime do to compost?’ to find out more.

Hedge trimmings, weeds and lawn clippings

Anything that has become over grown in the garden or out-served its usefulness, including dead flowers, can be turned into compost. Lawn clippings are the easiest material that you will ever find for making compost. It works really well when you mix lawn clippings with other ingredients which don’t rot down so easily.

Hedge trimmings rot very easily if you put them through a shredder. Small particles rot down very quickly because there is a bigger surface area for the micro-organisms to work on. While you have the shredder running, put through any weeds that you’ve pulled up. Chopping this will mean that they will rot down as fast as lawn clippings.

Getting the balance right

There are those who will tell you that you can’t make compost from various fruit or vegetable items. The thing is, if you have a mixture of all types of organic materials it will all rot down. The waste from an average, shall we say normal, household will present a mixture of waste material destined for the compost bin.

What can you put in your compost bin? Anything that’s carbon based and once living.

If there is a sudden influx of orange peel loaded into the compost, it won’t affect the entire contents of the bin. It may affect a small isolated area for a while before it breaks down and goes the same way as the rest of it.

Paper and cardboard

This isn’t put in compost to get rid of it as a waste in the same way as needing to get rid of green waste from the kitchen or garden. Paper and cardboard provides the carbon factor that balances the abundance of nitrates that can be found in almost all waste from the kitchen. It is a necessary ingredient and you need to aim for an inclusion rate of 20 carbon to 1 nitrates.

Lawn clippings and general waste generated from the garden won’t need the addition of paper or cardboard. The majority of what you gather from the garden will be largely carbon based. This being due to the fact that growing plants, whether it be grass or woody hedge trimmings, will have fixed carbon from the atmosphere.

Why should I make compost?

There are two main reasons why you should make compost.

The first is for yourself. If you have a garden which will always need natural organic feed for the plants that you grow, all of it will benefit from well made compost. In particular everything in the vegetable patch. If you have heavy clay soil (bad luck if you do) then a good dose of compost will attract worms and bring what you have to life. If you haven’t been making compost and then start doing so, you will find that you won’t be able to make enough. If you start, it will grow on you.

The second reason is to do something to help the community. If everybody made the effort to make compost then it would take an enormous load away from the national waste disposal services. Landfill sites are taking in thousands of tons of green waste. It’s costing all of us money that could be used better just about anywhere else. If you don’t have a big enough garden to be able to make use of the compost that you could make from your own waste then consider making it for someone who has. How about doing a swap, compost for vegetables.

Does making compost generate CO2

Yes, CO2 is generate when making compost. Should you worry about it? No. The earth has an atmosphere that has a measure of 0.04% CO2. There is an argument that there isn’t enough CO2 in the atmosphere and that plants all over the planet are constantly struggling to get enough.

When a tree falls over in the forest and no one cuts it up and uses it for planks or fire-wood, it will eventually rot. As it does this, much of the CO2 that was drawn from the atmosphere during the life of the tree, will be released back into the same atmosphere. This is going on all over the world all the time and has been happening for millions of years.

CO2 is generated in exactly the same way when we make compost. So, your kitchen and garden waste will generate all the CO2 that nature allows it to do when you make compost from it. The fact that you are making compost from waste doesn’t mean that CO2 wouldn’t be generated from that waste if you didn’t do it.

If the same waste was taken away to a landfill site, it would still rot down and release CO2. The difference would be that it’s out of sight and out of mind. The waste would have been transported to the site and you wouldn’t have the benefit of the compost that would have been produced.

On occasions, methane gas may be generated when compost is being made or when any organic material rots. The methane molecule is very unstable. When it disperses in the atmosphere, it will break down into CO2 and water.

CO2 is soluble, just like oxygen. Much of the CO2 in the atmosphere will dissolve in rain water. It will then fall to land and eventually find its way into the sea.

The sea has about 50 times more CO2 than the amount of CO2 in the atmosphere. The CO2 that’s generated, from whatever source, becomes the main part of the carbon cycle. CO2 is released into the atmosphere, then it’s re absorbed by every plant that lives on planet earth.

Through photosynthesis CO2 is combined with water (H2O) to form a hydrocarbon molecule. This is the base building-block for every plant that we know of. When the plant is digested or allowed to rot down, the CO2 that was taken from the atmosphere, will be returned to be used again.

What do I do if my compost bin is full?

First of all, congratulations to you. You have a full compost bin. Your diligent routine has served you well. So, what do you do now that your compost bin is full? You could put your waste in the trash can to go to the dump but I wouldn’t do that. You’ve started so why not finish?

It depends on how long it’s taken to achieve a full compost bin. If it has taken over a year then my guess is that you will have some really good quality compost at the bottom of the full bin. Now would be a good time to dig it out and use it. Put it on the vegetable patch or around shrubs and growing flowers. It will only be the lower portion that will be rotten enough to use.

When you remove compost from the bottom of a full bin you will create a void. After a short while everything above it in the bin will drop down, a little at a time, until the level at the top will have dropped. This will make more room for fresh waste. This is the ideal way to manage a static compost bin because every time the contents drop down in this fashion the compost becomes aerated. Getting air into it will accelerate the process more than anything.

If it’s taken six months to get to a full bin, then I would consider getting another compost bin, dig out the entire contents of the full bin and load it into the second bin. Moving it over will mix air into the forming compost and help it to rot faster. Alternatively, if you don’t feel like doing the work, just start filling the second bin with fresh waste. This will leave the first full bin to continue rotting down, it will do so over time. Then you can start removing compost from the bottom of the bin and load in at the top.

Does it make a difference if I use a bin or compost tumbler?

The main difference between a bin and compost tumbler are that the contents of a compost bin will stay motionless as you add more waste material. A compost tumbler is designed for turning over. This makes it easy to open up the contents of a compost tumbler, allowing air to get in and complete the decomposition process.

You can use a stirring probe in a static bin to introduce air but the occasional rolling of a compost tumbler will make a big difference as this will affect the entire contents. A stirring probe works by pushing the probe down into the waste, pulling it up and twisting it as you pull. This will open up the structure of the mass of material in a static compost bin.

A compost tumbler will open up the material but will do it much more efficiently. The tumbling action will completely break apart the mass, allowing air to get in. This is much easier to do with a tumbler and so it’s much more likely to be done.

We will still have the same issue about what to do when a compost tumbler is full. A tumbler will have a mixture of old compost that will probably be fully formed and fresh waste that’s been recently added. Because you will be wanting to load fresh waste into the tumbler, the best thing you can do is to unload the entire contents and put it in a static compost bin.

Because the compost from the tumbler will be in an advanced state of decomposition it will carry on forming into compost in a static bin. Any recently added fresh waste will easily break down with it, especially being well mixed in with the rest of the compost.