Composting at home.

Home Composting Guide

My first compost pile wasn’t great. A corner of my garden behind my garage had three walls around it, and I simply dumped my garden waste there. I didn’t pay much attention to the intricacies of composting, but when I dug down after two years I got compost.

You see while you can dig deep into the intricacies of composting, if you’re patient it’s pretty hard not to get compost – eventually. But at the same time, by getting some of the basics right, you can get better compost, faster, in a way that is more optimal for the environment. You certainly shouldn’t have to wait the two years that I did!

In this post we’re going to cover the bare minimum of what you need to do, without getting too deep into the intricacies, and avoiding jargon where possible.

Why compost at home?

Around 40% of organic waste is currently sent to landfill, where an inefficient breakdown process leads to harmful greenhouse emissions. Yet in just a few minutes a day, you can turn this waste into “black gold,” a valuable resource for plants and gardens, boost the health of your soil and save money at the same time. Composting is easy, fun – and can help motivate you to weed your garden too!

Compost bin or compost pile?

A large compost pile generating steam in the early morning.
A steaming compost heap. Image by Andrew Dunn.

First you need to decide if you want to use a compost bin or a compost pile.

A compost pile is free, and requires no initial setting up other than dumping your compost in one place. Piles are ideal for composting large amounts of material. However, the structure of the compost is harder to maintain. When it gets to a certain size it leans over, and as you don’t have a structure to keep the compost pile together, the composting process can be less efficient.

Compost bins require either some (easy) DIY, or an investment in a bin. Compost bins also have the advantage of maintaining the structure, and some bins are insulated, which can help keep the compost warm, speeding up the composting process. If you have a large amount of waste to compost, and want to keep costs down, you can always create your own compost bin using pallets for little more than the cost of a few screws.

How big should your compost pile be?

Some guides will tell you that your compost pile should be at least 3’ x 3’ x 3’. That’s because this size really helps speed up the composting process, generating heat in the process and killing pathogens and weed seeds.

It’s true that a larger size will help you get compost more quickly, but it’s not essential. In fact, I’ve found that it’s possible to create compost in a very small bin. It does take longer, and it’s best to avoid adding perennial weed seeds as these will not be killed by the heat. Alternatively, you could use an insulated compost bin, which can produce heat despite the smaller volume used.

Thermometer showing 60 degrees celsius.
Hot compost with an insulated bin.

You should avoid adding cooked food and dairy products to a cold compost, as these will not be quickly consumed by the compost bacteria and are likely to attract mice and rats. Fortunately, the worms that will be attracted to your compost pile will do a good job of destroying any harmful bacteria.

Siting your compost

If you have a large garden, it’s a good idea to place your bin (or pile) in the centre of the garden. That means that whatever part of the garden you are working in, it’s easy to reach the bin with your garden waste. It’s also easy to transfer your compost to any part of the garden when it’s time to use it. Alternatively, if you are planning on composting mostly kitchen waste, it’s a good idea to place your compost near the kitchen, a fact that occurs to me regularly as I trudge down to the bottom of my garden in the depths of a cold, wet winter night!

While not essential, it’s also a good idea to site your compost bin in shade or partial shade, especially if you live in a hot climate, as compost benefits from a constant temperature, and too high a temperature in your bin can kill helpful bacteria.

If possible, you should place your compost bin on bare earth. The bacteria and fungi from the soil will help get the compost going, and it provides an easy entry for the worms which will help finish off the composting process. But don’t worry if you can’t. You can always add some soil to help get the compost started. Worms will find their way to their bin eventually, but you can speed up that process by adding some tiger worms (you can either purchase these, or go on a hunt to find some yourself).

If you have a large garden, it’s well worth thinking about future expansion. For example, you might start off with a single compost bin, but later on expanding to a two or three bin system, allowing for regular turning. So if you have room, try to site your bin so that there is space to additional bins in the future.

Finally, it’s great if you can place your compost heap/bin on level ground. If you don’t have level ground, it’s well worth spending a little bit of time with a spade to create a flat bit of space. That will avoid water gathering in pools at the bottom of the compost pile.

See Siting your Compost on Home Composting Made Easy for more ideas and guidance.

What to put in your compost

A mixture of greens and browns in an insulated compost bin.
My compost bin with a mixture of greens and browns. The shredded paper helps absorb excess liquid.

Most organic materials, from weeds to food scraps and paper, can go in your compost bin. However, bear in mind that cooked food and dairy products should not go in a cold compost heap, and that woodier materials will take much longer to break down.

In an ideal world, you’ll get a roughly even mixture of brown and green material in your compost pile, or a little more green than brown.

Brown here refers to materials high in carbon, such as cardboard, paper and leaves. Greens refer to items high in nitrogen, such as grass and weeds. It’s important to remember that not all greens are green – coffee, for example, is also high in nitrogen, and so is called a green despite being brown in colour.

We’ve written in depth about the carbon:nitrogen ratio here, but you don’t want to worry too much about it. Everything has a different carbon:nitrogen ratio, so unless you want to use a reference table and a weighing machine every time you add compost, it’s just not worth spending too much time thinking about it.

Breaking it up

Composting will also take place quicker if you use smaller materials. By breaking up the material, you are providing a greater surface area for the bacteria to work on. I don’t always bother doing this with large compost heaps (they seem to heat up anyway, and life’s too short to chop up every piece of material), but it can be very helpful in speeding up the process with smaller bins.

Ideas for breaking up your compost can include mowing it with your lawnmower (very effective in terms of getting smaller compost pieces, but it can be a bit messy) or putting it in a bucket and roughly chopping it up with a pair of large shears.

Water

The bacteria in compost needs water to turn waste into compost. But if you add too much water, the composting process will take longer, it’s not as good for the environment and you could get a (slightly) unpleasant smell. If you squeeze the material in your compost it should feel like a squeezed out sponge.

Too avoid getting water in your compost, it’s a good idea to cover it over at times of rain. Plastic sheeting will stop rain getting in, while a carpet has the added advantage of adding insulation and warmth. If it does get too wet, adding in shredded paper or torn up cardboard will help absorb the water.

If your compost gets too dry, you can add water. This is important if you are turning the compost, as very dry compost can lead to bacteria that is harmful when breathed in.

Airing the compost

Ready for turning.
In this bin I have mustard growing, ready for turning into the compost.

The same bacteria that needs water to reproduce also need air. Many compost guides advise turning your compost every couple of days in order to get oxygen into the pile. There’s a good reason for this. When oxygen levels in the pile fall below 5%, the composting process can slow down by as much as 90%.

However, while it’s true that turning is a great way to speed up composting, and also ensures that the composting process applies evenly to all the material in the pile, it’s too much work for most people. In fact, I only turn my compost heap twice, and some people turn it once, or not at all.

There are other ways to get air into your compost. Creating a base of branches and twigs at the bottom of your compost heap helps create air pockets. You can also raise the base of the compost bin in order to ensure air flow around the bottom of the heap.

You can add in materials such as scrunched up cardboard or wood chips (semi-decomposed is ideal, as fully fresh wood chips take a long time to break down) as you build the pile in order to create air pockets in the compost.

Finally, you can use a metal pole to stick into the compost to create additional air flow as the months go on.

Letting it mature

Even if your compost heats up and is ready in a few weeks, it still needs leaving to mature. Fresh compost is raw, coarse and can be acidic. This is when the worms start to work their magic, breaking the compost down further, improving the quality with their castings and removing harmful bacteria such as e-coli.

Ideally you’ll leave your compost for a few months before finally using it – the longer you leave it, the better it is likely to be, although of course you have to balance perfection against the needs of your garden! When it’s looks and smells like rich earth, and bears little resemblance to the original material (except for the odd bit of wood), it’s ready to be added to your soil. Some people sieve it at this point, but it’s not strictly necessary unless you plan to be planting seeds in it.

When you’ve finished your compost, simply add it to the top of the soil for a no-dig approach to gardening (hugely beneficial for the soil) or dig it in for a more traditional approach.

Further reading:

The Eden Project has some great tips and a video for the new compost maker

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