Learning how to compost is a very useful skill for a gardener: not only is it an environmentally friendly way to dispose of your organic and biodegradable waste, but it's also an easy and cheap way to produce your own, high-quality garden fertiliser. There's a bit more to it than 'throw it all on the compost heap', however. So, in this guide, we help you master the art of garden composting.
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How to compost: what can go in
The main ingredients for compost are:
- Green waste: Between a quarter and half of your compost should consist of organic waste, primarily from vegetables and fruit. Cut grass from your lawn and weeds are also great sources of green waste for your compost.
- Brown waste: This is the dry waste that is going to help aerate your compost, and prevent it from getting too wet and rotting as opposed to composting. Use dead, dried plants, shredded paper and cardboard. If you have too much brown waste in your compost, your won't get the rich, soil-like compost texture in the end.
How to compost: what can't go in
The most important thing to remember is that your composting bin is not simply a bin for all your organic waste (that's what you kitchen caddy is for). Compost bins shouldn't include meat, fish, or dairy waste – you won't get the right balance of nutrients, and worse, you might end up attracting vermin to your compost bin.
Compost accelerator: do I need it?
The answer is, 'not really', so long as you have the right balance of green and brown waste in your compost mix. Compost accelerators are rich in nitrogen and are meant as a substitute when there isn't enough green waste, but they don't accelerate the process as such, and you shouldn't need them if you are composting correctly.
Compost bins: how to choose the right one
Choosing the correct compost bin is crucial to correct composting. Ideally, you want a bin that's made from metal or wood, not plastic. A proper garden compost bin should have ventilation and drainage (think a slatted construction), and contact with the ground, because the soil will activate the composting process. It should have a cover to protect your compost from the rain, or you'll end up with a mixture that is too wet.
If you are using a kitchen composting bin, again try to use a metal or ceramic one, and keep it away from direct sunlight – under the sink is a good location. Line the bottom of the bin with garden soil to aid the composting process.
For both indoor and outdoor compost bins, the larger the size the better. You can also do without a bin and use a shady corner of the garden instead, but it's best that the area is covered by a tree or some sort of canopy to protect it from the rain.
Turning compost: how and why
Turning compost is important because it adds air to the mixture, which is essential for the chemical processes that make the compost. Not enough air can result in a compost that is compacted, slimy, and/or rotting. This is often the case in small-scale home composting, when you're adding a bit of waste infrequently. For best results, turn your compost as often as you can with a pitchfork – or, if you're composting in the kitchen, with whatever kitchen utensil with a long handle you can find. For larger compost bins, you can also use a compost aerator, which pumps air into your compost.
If you really don't want to bother with turning, try layering your compost, making sure that there's ample brown waste between layers of green. This should prevent your compost from going too soggy.
How long does compost take?
Depending on the average temperature, and materials you're using, and how well the compost is aerated, it can take anywhere between several months and over a year for compost to mature enough to be ready to be used in your garden. How will you know it's ready? Garden compost should have a rich, crumbly texture, a uniform brown colour, and a smell of damp earth. You may find that not all the compost in your bin/heap will mature at the same rate, or that you may end up discarding some of it.