Building a good compost heap
First, choose a shady spot in the garden for your compost bin, enclosure or heap. Too much sun will dry out your compost. Then set up a separate bin in the kitchen for food scraps.
To make good compost quickly, your compost needs food, air and water.
Feed your compost with a mix of 'greens' and 'browns'. Greens
Browns - dry materials
- Fruit and vegetable scraps
- Tea leaves and bags
- Coffee grounds
- Green leaves
- Dead flowers
- Weeds from the garden (avoid noxious weeds)
- Blood and bone
- Fresh horse manure
- Dry brown seedless weeds
- Autumn leaves
- Wood chips
- Shredded newspaper
It is not recommended that you feed your compost with
- Animal fat
- Animal manures, especially the droppings of cats and dogs
- Bread or cake (as may attract mice)
- Diseased plants
- Large branches
- Meat and dairy products
- Metals, plastics, glass.
- Sawdust from treated timber
- Weeds that have seeds or underground stems.
If you want to put noxious weeds in the mix, place the weeds in a plastic bag for a week or so to kill them first
Make sure that your pile has enough air by:
- Turning the pile regularly by breaking it apart then piling it back, at least once a week.
- Breaking up clumps of food waste.
- Punching holes in the container or inserting a slotted pipe in the heap. The pipe will help to bring air into the centre of the heap.
- Putting twigs and newspaper in the mix to increase airspaces.
- Adding some compost worms (you'll need about 2,000 to start).
- Don't let it become too wet
All living creatures need water, even microbes, so keep your compost as moist as a wet sponge. A dry pile makes composting too slow.
However, if the pile is too wet, the ingredients become heavy and exclude air from the pile, slowing the composting process and creating bad smells.
Using Your Compost
After 4 months or so, when the compost is dark and crumbly, it will be ready to use. Dig it into your garden beds or spread it on top of an established garden as mulch. Always wear gloves when working with compost and take necessary health precautions.
Compost Containers and Heaps
There are many types of home composting containers, including:
- plastic bins with ventilation holes or slits
- plastic bins without ventilation
- metal drums with holes punched in the side and with the base removed
- rotating drum units (tumblers)
- enclosures made from timber (planks or sleepers), bricks, or chicken wire.
The Layering Method (Slow and Cool)
Add a mixture of materials. Try to add alternate 10 cm layers of vegetable and fruit scraps, grass clippings and leaves and shredded newspaper.
Cover each layer with a thin layer of soil and a handful of fertiliser, such as blood and bone.
Keep moist, but not too wet. Compost should be as wet as a damp sponge. The compost should be ready in 3 to 6 months. Breakdown will be speeded up if the heap is turned weekly.
The 'All In Together' Method (Fast And Hot)
Store enough food and garden waste to make a heap of about one cubic metre.
Add to a bin or a tumbler, or form into a heap with some fertiliser.
Turn several times a week. The heap will generate a great deal of heat as the rate of breakdown is very high. The compost should be ready in 3 to 6 weeks.
The Compost Worm Method (Moderately Fast And Cool)
Build the heap slowly as for the layering method, but add some compost worms (special worms that thrive in compost) to the bin. Start with about 2,000 worms.
Keep the heap well watered, but not too wet. Turning is not necessary as the worms will turn the heap for you. The completed compost should be ready in about three months.
Worms do not survive in temperatures above 30oC so keep the bin in the shade. There is some doubt about whether worms are capable of killing weeds and diseases, as they might digest some weeds and ignore others. Worms do not digest seeds but love cardboard. More research in this area is needed.
Note: There is a lot of variation in printed materials about how to compost. This sheet provides information about what is believed to be commonly accepted practices.
Health Precautions with Compost
Compost is produced from natural materials and contains a variety of living organisms. On rare occasions, these organisms have been associated with illness and allergies in humans. For health reasons, it is very important to take the following health precautions when handling compost:
- Wash your hands after handling compost or soil materials
- Protect broken skin by wearing gloves
- Avoid confined spaces for handling compost or soil materials
- Keep compost moist to prevent spores or bacteria from becoming airborne
- Gently moisten dry compost to allow dust-free handling. Avoid inhalation of dry compost.