WHCA compost monitor John Stokdyk offers some insights into the magical processes taking place within your friendly neighbourhood compost bin.

MAKING COMPOST IS like preparing a meal for hundreds of worms, thousands of insects and millions of microbes and fungi. You want to stir up a hearty vegetarian stew to attract all these guests, who will make compost for you by eating it. The basic ingredients are:

• Green things like plant cuttings, farmyard manure and veg scraps that are rich in nitrogen
• Brown stuff such as cardboard, paper, straw and twigs that are rich in carbon
• Air to let the creatures that do the composting breathe, plus a little water to keep the mixture moist

Worms are voracious and indiscriminate eaters, but, like picky children, they are not so fond of certain foods. The things you shouldn’t put into a compost bin include:

• Citrus fruit and members of the allium family (onions, leeks, shallots, garlic)
• Meat, dairy food and cooked leftovers. They go smelly and can attract rats and mice
• Too many autumn leaves at once. Left in a plastic bag or leaf pen for a year or so, they’ll decompose into leaf mould that you can then mix into your normal compost

The guiding principle is balance. Too much of any single ingredient can slow or stop the composting process, but you can usually get it going again by adjusting the mix. At this time of year a well aerated, regularly stirred compost bin can ‘cook’ really quickly. Within six weeks or so of putting material in, it should have broken down to useable compost that is uniformly brown and crumbly.

Fresh compost like this can be a little strong for applying directly onto plants, so try and let it rest a little longer before use, or mix it with some leaf mould and apply it as a mulch to improve and condition your soil.