Create your own compost

CompostComposting is the accelerated natural breakdown of organic material by microorganisms. The resulting material can be used as an alternative to artificial fertilisers as it provides the full range of nutrients required for plant growth.

Compost can either be made in a pile or bin, depending on the amount of material for composting and the needs and size of your garden. A compost pile is useful for gardens with large quantities of greenwaste and a bin is often better suited to smaller suburban gardens. Compost bins can be purchased from your local hardware store or nursery, or you can make your own.

If compost is turned regularly, it should be ready for use in two to three months. By this time most of the ingredients have broken down into a balanced soil food.

How to make your own compost

  • Choose a level spot in the backyard with some exposure to the sun, especially if you are using a smaller bin
  • Always begin by using twigs or sticks at the bottom for proper aeration and drainage
  • Then add kitchen scraps and garden waste to the top of the pile
  • Keep the compost moist, and not soaking wet
  • Turn it once a week if possible – this will speed up the process, ensure adequate aeration and reduce the likelihood of unpleasant smells
  • After 3-12 months the compost will be ready to use. Dig it into new garden beds or spread it on top of established gardens
  • The length of time it takes for the process to occur will differ depending on the material used for composting, the amount of air and water available and how often the compost is turned
  • When your compost is finished it will have a fine, crumbly texture and a good earthy smell.

How to use compost

Your compost can be used in a variety of ways such as:

  • An organic fertiliser for garden beds, providing all essential plant nutrients
  • Surface mulch around shrubs and trees –the mulch should not touch the tree trunks
  • A top dressing for the lawn – you may have to sieve the compost
  • A potting mix for potted plants, using a ratio of 1:1 with garden soil
  • To replace or improve lost and disturbed topsoil.

Green foods (nitrogen rich)

Aim to have about 25% of nitrogen rich (green) materials in your compost, including:

  • Leaves (green prunings)
  • Grass (green clippings)
  • Cow, horse or chicken manure
  • Fruit and veggie scraps
  • Coffee grounds
  • Tea bags
  • Hair from your brush and comb

Brown foods (carbon rich)

Aim to have about 75% of carbon rich (brown) materials in your compost, including:

  • Dried leaves and dried grass clippings
  • Sawdust (not treated pine)
  • Wood shavings (not treated pine)
  • Hay and straw
  • Vacuum cleaner dust
  • Shredded paper
  • Newspaper

What not to compost

Some organic waste items may encourage vermin such as rats, flies and cockroaches, and will smell when they decompose. Some items to avoid include:

  • Fats and oils
  • Meat products
  • Dairy products
  • Bread and cake products
  • Cat or dog excrement
  • Man-made materials such as plastic, steel, aluminium and glass

Maintain your compost

Once established, you should use the popular A.D.A.M principle of composting:

  • A is for aliveness – when there are micro-organisms, bugs and worms living in your compost, it is working well.
  • D is for diet or diversity – make sure there is a range of different materials in the compost, and in the right proportions i.e. 25% green, 75% brown.
  • A is for air – turn your compost every week so there is plenty of air moving around. This reduces bad smells and helps the material break down faster.
  • M is for moisture – damp but not wet compost works best.

Compost problems and solutions

Listed are some problems that may occur, the cause and some useful solutions.

Problem Cause and solutions

Smelly compost

Material is too wet:

  • Incorporate dry materials (e.g. leaves, straw, dry grass, torn newspaper or egg cartons)
  • Cover pile to prevent infiltration of rain water.

Not enough air:

  • Turn the heap to improve drainage and aeration
  • Incorporate coarse materials (twigs, prunings, leaves)
  • Establish pile or bin on layer (10 cm) of coarse materials
  • Increase aeration of compost pile or enclosure by using a perforated aeration pipe or by adding more aeration holes to compost bin.

Slow composting process

Too much woody material:

  • Add more easily degradable green materials (grass clippings, garden plants, kitchen scraps)
  • Incorporate appropriate amount of nitrogen-containing fertiliser (e.g. blood & bone).

Material is too dry:

  • Turn the pile and add water
  • Place pile/bin in a shady location
  • Cover pile to retain moisture
  • Pile is too small to heat up:
  • Increase size of pile to at least one cubic metre
  • Cover pile to retain generated heat (e.g. plastic, hessian, old carpet).

White maggots

Food scraps:

  • Do not compost these materials
  • Cover the maggots with lime
  • Add soil to cover food scraps
  • Do not use an enclosed bin composting system.

Brown segmented larvae

Not enough air:

  • These are soldier fly larvae, which are beneficial for the composting process
  • However, they may indicate that there is not enough oxygen in the compost pile, which might result in unpleasant smells.

Small vinegar flies

Fruit:

  • These are not fruit flies. Vinegar flies are harmless
  • Cover fruit remains with other materials
  • Do not add fruit remains.

Pile is too acidic

Addition of fruit over time:

  • Add lime to neutralise naturally formed acids (sprinkle lightly)
  • Turn pile more frequently and ensure good aeration.

Vermin

Easy access to food scraps:

  • Use fully enclosed composting bin (e.g. tumbler)
  • Put fine wire mesh underneath the pile/bin
  • Cover food scraps with soil or garden remains
  • Do not compost food scraps.

Mice nesting in pile:

  • Turn pile and keep it moist.