Composting is an excellent way of recycling waste and producing a superb soil fertiliser and conditioner.
Living microscopic organisms, like bacteria, break down the household and garden materials we put in the compost by feeding on them. They need food, air and moisture to thrive.
Good compost can take between 6 - 12 months to develop depending on the conditions. When it's ready it will be dark brown, have an earthy smell and be crumbly. When you come to use the compost, it may be lumpy or have bits of twig and large uncomposted material in, but if you sieve it then these bits can easily be put back into the compost to finish the process. Good compost uses a 50/50 balance of different types of materials, known as greens and browns. Grass cuttings, fruit and vegetable peelings and other wet sappy material are greens; dry, woody material like old bedding plants, hedge clippings, leaves, shredded newspaper and cardboard are browns. Greens rot quickly to start the heap by adding nitrogen to the mix, while browns add structure to allow air in and provide the microbes with balanced nutrients.
Air is vital to the decomposition process because the microbes need it to live, and can be introduced to the heap in a number of ways.
- By adding scrunched-up paper, cardboard egg boxes or even loo roll tubes to trap air
- By using an implement to stir the heap, for example a compost aerator
- Fork the heap over (hard work with a large heap and not practical if you have a narrow-topped compost bin)
- Buy a tumbling or rotating compost bin to do the work for you.
If the balance of greens and browns in your heap is correct then you should have a barely moist mix with no offensive smell. Try adding more browns if the mix smells and is wet, and conversely try adding more greens if it is too dry (if the heap has ants it is probably too dry). A dry heap will rot slowly, but you can help it along by adding a small amount of water and mixing it in to incorporate air too. Alternatively, human urine can be added to the heap - this is a natural source of nitrogen and potassium too, so it encourages faster breakdown. Be careful not to add too much though as excess will raise salt levels and discourage worms.
Another ingredient essential to the success of a compost heap is warmth. If you site the bin in partial sun and use a lid then this combined with the heat it generates in the decomposition process should work nicely. If you don't have a lid, or if your heap is too small to generate a good heat, then cover it with a piece of old carpet or a thick layer of cardboard instead. Cardboard will itself rot down of course, so you can keep adding waste on top of it if you like.
Assuming you have satisfied all these requirements so far, and the compost is still not developing quickly enough for you, there are other things you can do to speed up the process. Chopping your greens into small pieces and shredding your browns is an obvious starting point. You can add nitrogen-rich plants like nettles, comfrey and grass cuttings to the mix. Grass cuttings should always be mixed with fibrous browns to balance the nitrogen and maintain air pockets, otherwise your heap may become too wet leading to slimy and smelly compost. There are other tips for using grass cuttings here. Tumbling composters are advertised as making compost faster, and this is because the turning introduces air and keeps the greens and browns mixed well.
Take care when composting weeds and poisonous plants. Annual weeds are fine to go in (including chickweed and speedwell) as long as they have not run to seed. If they have, treat them as perennial weeds like couch grass, dandelions, bindweed, thistles etc., which should preferably be chopped up before being tied up in a bin liner with no holes, placed in the sun and left to rot down. They can be added to the heap when they are thoroughly rotted down. Poisonous plants like privet, laurel and yew are best composted separately - evergreens take longer to break down so mixing with grass clippings is a good idea to aid the process. They can be used as mulch around trees when thoroughly composted, again 6-12 months.
Do NOT put cooked food, meat or fish, bread, cat & dog faeces, dairy products, nappies, coal ash, glossy magazines or junk mail into the compost. There are separate disposal units you can buy if you would like to dispose of these things, please follow this link.