Worm farming

Feeding leftover fruit and vegetable scraps to a worm farm is a cheap and easy way of recycling organic waste.

Worm farms will turn your organic waste into worm castings and ‘worm tea’, which you can use to fertilise your garden.

What you can add to your worm farm

Worms will eat almost anything. However like us, there are things that are good for them and things that are not. Worms like to eat:

  • fruit and vegetable scraps
  • egg shells
  • shredded paper products
  • fallen leaves
  • tea bags
  • coffee grounds
  • lawn clippings and weeds.

Worms don’t like to eat

Worms don't like to eat:

  • meat products
  • dairy products
  • oily products
  • onions and garlic
  • large quantities of bread
  • oranges, lemons and limes.

You can buy worm farms from garden centres and hardware stores. You can also build your own.

Polystyrene worm farm – build your own

What you will need:

  • two polystyrene fruit boxes with lids
  • a lining for the bottom of one box – you can use a strip of insect screen, hessian bag, cardboard or newspaper
  • a bucket of 'bedding' material – a coir-peat brick is ideal (available from most hardware and garden centres)
  • at least 1,000 compost worms. The most common compost worms are tiger worms, red wrigglers and Indian blues
  • a loose cover, such as hessian bag or a whole newspaper
  • fruit and vegetable scraps from your kitchen.

Building your worm farm

  1. Choose a place for your worm farm – somewhere that is well-drained, protected and shady.
  2. Punch holes in the bottom of one box. This will be the top box where your worms will live.
  3. Take your second box and make a drainage hole near the base, at one end. The worm tea will drain from the top box down to the bottom box and out the drainage hole. Place a container under the drainage hole to catch the worm tea.
  4. Place the lining in the bottom of your top box. This will stop the worms from falling through the holes.
  5. Add a 10c- thick layer of bedding material to the bottom of the top box.
  6. Add the compost worms and then place the loose cover on top. Place the lid on.
  7. After one week, add some fruit and vegetable scraps into one corner of the worm farm.
  8. Add water every now and then to stop the worm farm from drying out.
  9. Keep adding fruit and vegetable scraps every week. Place the scraps in a different corner each time. If any scraps are uneaten after five days then you know you have fed them too much.

After a few weeks, the worm tea will drain into your container. Add some water until it is the colour of weak tea and pour it on your plants.

After a few months, a layer of worm castings will build up in the bottom of the top box. Set up a new box and transfer your worms in there to live. Then you can collect the worm casting from the bottom of their old home.

Worm tubes - build your own

Worm tubes are feeding stations where worms and other insects can come and go as they please.

The worms and insects enter the tube to feed. Then they exit the tube and move around your garden, taking worm castings and other nutrients.

What you will need:

  • an empty 10L or 20L bucket with lid.

Building your worm tube

  1. Choose a place for your worm tube – ideally somewhere that is shady, near shrubs or in a vegetable garden.
  2. Remove the base of your bucket and drill holes in the lower third of the bucket.
  3. Dig a hole in the garden and stand the worm tube in the hole. Push soil up around the bucket to cover the holes.
  4. Place some food scraps and other organic matter in the bucket and put on the lid.
  5. Add a couple of spoons of garden lime or dolomite every 4 to 6 weeks. If you have any problems with your worm tube, pull it up and cover the hole.

A worm farm needs a balance of organic materials, moisture and air to create the right environment for worms. If you have a problem, the following chart may help.

Worm farm trouble shooting

Some causes for strong, bad smells are:

  • Not enough air circulation 
  • Too much food in bin
  • Improper food added
  • Anaerobic conditions 

Some ways to help with strong, bad smells are: 

  • Fluff bedding and make sure bedding or compost is not blocking air holes
  • Feed worms less, or less often
  • Remove meat, dairy and oily product
  • Add some dry bedding to absorb moisture

Some causes for fruit flies are:

  • Food exposed
  • Too much food

Some ways to help stop fruit flies are: 

  • Cover food and bedding completely
  • Feed worms less, or less often

Some causes for ant infestations are:

  • Dry conditions 

Some solutions for ant infestations are:

  • Bedding may be too dry - dampen with some water

Some causes for mite infestations are:

  • Mite population is high 

Some solutions for mite infestations are:

  • Avoid adding food with high moisture content, such as fruits and vegetables

Some causes for overly moist worm farm are:

  • Too much water added to bedding
  • Too much food with high moisture content 

Some solutions for overly moist worm farms are:

  • Stop adding water and add some shredded paper to soak up extra moisture
  • Put in less fruit and vegetable waste and add some shredded paper