Making compost

Compost heaps can be designed to suit gardens of all sizes. You can build your own or choose from a whole range of specially designed bins, available at garden centres and through internet and mail order outlets. Some local councils now offer subsidised compost bins. A larger garden can easily accomodate a simple heap in a lesser used part of the garden, while even the smallest terrace could accomodate a worm composter.

To erect your own bin, hammer into the ground four 10cm x 10cm (4in x 4in) posts to enclose an area about 1sq m (40sq in.) Then bash the soil with the back of a spade to consolidate it. Next either tack wire netting to the posts, or nail planks around them, leaving the front side easily detachable so you can get the finished compost out.

Once you have chosen a compost bin and site for it there are a few simple rules to follow. Ideally start your compost bin in spring and for best results combine a mixture of soft, green, nitrogen-rich material and dry, brown, carbon-rich material in roughly even quantities. The main rule is not to let one material dominate the heap. A glut of autumn leaves will decompose very slowly and would be better used making leaf mould.

Place the more woody material at the bottom to help with air circulation and layers of different materials at least 30cm deep. Shred larger items so they decompose more easily and if the waste is very dry, spray with water to moisten the pile, but do not soak it.

Keep adding to this initial pile at regular intervals. When the heap or bin is full, it will start to heat up as the decomposition process gets underway. After a couple of weeks when it begins to cool down, turn the heap with a fork, mixing up the contents thoroughly and adding water if it is drying out. If turned regularly and in warm conditions your compost will be ready in about 2-4 months.

A heap left unattended and using bulkier, unshredded material may take over a year to fully decompose. When the compost is finished, the pile will be about half its original size and have an earthy smell to it. If you want a fast turnaround, create a hot compost heap by adding nitrogen, moisture and turning the heap regularly to improve the air circulation. When the heap begins to cool down slightly, turn the heap to introduce oxygen and undecomposed material into the centre and regenerate heating. The composting process is complete when mixing no longer produces heat in the pile

Green, nitrogen rich material

• grass cuttings
• soft prunings
• annual plant and weed remains before they have set seed
• fruit and vegetable scraps
• old cut flowers
• tea bags and coffee grounds

Brown, carbon-rich material

• cardboard
• paper bags and scrunched up paper
• straw and small animal bedding (vegetarian animals only)

• diseased plants
• meat and fish
• cooked food
• coal ash
• cat and dog litter
• disposable nappies
• glossy magazines and cardboard
• perennial weeds eg bindweed

A slimy compost heap is usually due to too much of one material such as grass clippings, and not enough air in the heap. To solve this problem, remove the slimy layer and add material such as straw, shredded hedge clippings or crumpled paper. Turn your heap periodically to get more air in. A cold compost heap doesn't mean it isn't decomposing, just that the process will take a little longer.

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