Photo by net_efekt.

This is a guest post written by Emma Cooper. She’s a freelance writer and podcaster from the UK. Check out Emma’s gardening blog at http://coopette.com/blog.

“Making your own compost has lots of benefits for a garden. Adding homemade compost to the soil helps to improve the soil structure without digging – meaning that the soil will retain water for longer in dry weather and yet drain better in wet weather. It also encourages a healthier soil environment, which leads to healthier plants.

Homemade compost can also be used as free fertilizer or mulch, or as part of potting mixes, saving you money. And by reducing the amount of waste we send off to be buried or incinerated, we’re helping to reduce the strain we put on the Earth. Even the wildlife in your garden will be grateful if you compost – rotting organic matter is food for lots of beasties at the bottom of the food chain.

There are lots of different methods of composting, and some of them can be quite daunting. If you want to build a ‘hot’ heap then you have to collect the right sort of materials until you have enough to build the whole heap in one go, in alternating layers. Once you’ve built the heap, you have to keep turning it every two or three days to get enough air into the compost to keep the temperature up. If you have the time, space, and energy it’s a great way to make compost – but it’s not the only way.

A simple and easy way to make compost is to build a ‘cold’ heap. In cold composting, you add materials to the compost bin as and when you have them – and you don’t have to turn the heap. The end result is still compost that’s perfect for using around the garden.

The golden rule of any sort of composting is that you need a mixture of materials. ‘Green’ materials are rich in nitrogen and include grass cuttings, kitchen waste and fresh plant material. Not all ‘greens’ are green, though! Coffee grounds are rich in nitrogen, too, and are a great addition to the compost heap. ‘Brown’ materials are rich in carbon. They include woody material like twigs, and also cardboard and paper.

The composting process relies on bacteria, fungi and small animals breaking down the things you add to the heap – and they need a balanced diet. In most households, it’s easy to feed a mixture of materials to the compost. Kitchen waste and garden waste can be balanced out with scrunched up cardboard or shredded paper.

If you add too many ‘greens’ to your compost then it will go a bit slimy and smelly; too many ‘browns’ will make it very slow to rot down. Compost can also be too dry – it needs to be quite damp, and you can add some water if necessary.

With a cold compost heap you have to be careful not to add any waste that could attract rats, and weed seeds and plant diseases that won’t be killed during the cold composting process.

‘Greens’ you can add:

Vegetable and fruit peelings, any uncooked vegetable waste
Coffee grounds and filters
Tea and tea bags
Wilted cut flowers
Old bedding plants
Young annual weeds
Poo from vegetarian animals

‘Browns’ to add:

Torn up cardboard
Egg boxes
Scrunched up newspaper or shredded paper
Twigs
Some fallen leaves (although a lot of leaves are better turned into leaf mould)

Don’t add:

Cooked food
Meat, fish or dairy products
Poo from meat-eating pets
Perennial weeds
Seeding annual weeds
Diseased plant materials

A cold compost heap doesn’t heat up in the same way as a hot heap, but it does get warm (especially in summer) and if you add waste every few days then one day when you go out to the bin you will notice that the volume of your compost has shrunk – a lot! At this point it’s useful to have two bins – so you can let the first one rot down and start filling the second – but it’s also possible to keep filling one bin from the top and extract the finished compost from the bottom as a continuous process.

Cold composting takes several months to produce finished compost (longer in the winter), and the longer you can leave your compost to mature then the finer it will be. Even so, when you remove your compost from the bin you will probably need to pick or sieve out some larger items that haven’t completely rotted down. You can add those back into the bin to start the next batch of compost. Homemade compost doesn’t look like potting compost that you would buy, it’s usually rougher in texture, but that doesn’t mean you’ve done it wrong!

Compost made this way isn’t ideal for starting seeds – it isn’t sterile and is likely to be quite rough – but it has plenty of other uses. Homemade compost is great used as a mulch around the garden, to cover bare soil or to feed hungry plants like fruit bushes. Just spread your compost on top of the soil, and let the earthworms do the hard work of incorporating it into the soil for you. Or, if you’re digging over a bed anyway, add the compost in as you go.

You can also use your compost as part of a potting mix in containers, by adding garden soil, sand or leaf mould. Sieved compost, mixed with sand, makes an ideal top dressing to feed the lawn. In fact, homemade compost is perfect for improving the soil anywhere in the garden, and feeding plants without using fertiliser, and the only problem you’re likely to have is making enough of it!”