Welcome to the worm farming section. Worm farming is fun, entertaining and informative.
IntroductionCompost can also be produced using worms. This is known as worm farming. It is also called ‘vermiculture’ or vermicomposting.
Usually tiger worms are used for worm farming in NZ, though red worms can also be used. Worm farming uses the same principles as composting, but it does not generate heat, making it cold composting. Value is added to the materials when they are eaten and excreted by the worms. This produces what is called vermicast and worm tea which have high levels of nitrogen, phosphorous and potassium (NPK) compared to ordinary soil. This makes them valuable for your plants’ leaf growth, root and stem strength and flower and fruit set.
To find out your local suppliers of compost bins, worm farms, bokashi systems and garden waste disposal sites please contact your local council. See the Contact us section for links to Create your own Eden partner organisations.
The benefits
Casts and worm-tea are fantastic for plants (always dilute the worm-tea to the colour of weak tea – usually about 1:10).
If you have mostly kitchen waste, live in a home with little or no outdoor space, a worm farm is a good option.
Kids enjoy them.

Getting Started

  • Choose a site which is sheltered from sun, wind and rain. Carports or sheltered porches are ideal.
  • Use a layer of bedding first – eg, hay/ coconut fibre/ shredded cardboard/paper.
  • Bedding should be damp and porous.
  • Food can then be added. You can cover food scraps with damp newspaper or cardboard to limit flies and odour. Worms eat about their own weight every day: 250g of worms will eat about 250g of waste.
  • Worms need air but not light (worms are photophobic).

Keeping it going

  • Worms need a moist environment.
  • Check that their surroundings are damp, add water if needed.
  • Add dry leaves or torn up paper products if it is too wet – the working area should be as damp as a wrung out sponge.
  • Add food scraps regularly.
  • Smaller pieces (no larger than 2cm) will be eaten more quickly and prevent odours.
  • Worms cannot tolerate very hot or cold conditions (10-30° is ok).
  • Small flies or white worms/bugs indicate the worm farm has become too acidic and you should add a sprinkling of lime to neutralise pH.
  • Worms are omnivores and will eat almost anything, however there are some foods that are best left out of your bin.

The diet

What worms like

Most fruit and vege scraps, coffee grounds and teabags, aged horse manure, dirty paper, crushed eggshells, vacuum cleaner dust and hair.

What worms don’t like

Spicy food, chili, onion, garlic, meat and milk products, flour products, large amounts of cooked food, garden waste, shiny paper, citrus / very acidic food.

Harvesting your worm casts

  • After a few months or when a layer is full, you should harvest the casts.
  • Remove the top layer and take off the bottom layer. This bottom layer contains the casts. It is ready when few worms can be seen.
  • Remove worm tea from the bottom level. (When using, dilute to the colour of weak tea, usually about 1:10)
  • When one working layer is full, you can add another layer to your worm farm.
  • Place new layer on top of the old one and then add bedding (paper/ straw/ manure) and then add more food scraps.
  • Add food only to the new layer. The worms will migrate slowly to the food layer.
  • If you have large layers in your bin and you want to harvest casts earlier, you could add a layer of chicken wire instead of a new plastic layer.

Common worm farming problems

Problem – Cause – Solution

Fruit/ vinegar flies around farm or small white bugs and worms

  • Too acidic – Cover food with damp paper. Add lime to increase pH

Worms climbing up sides. Worms very fat and pale

  • Too wet – Add paper products and dry leaves, gently fork holes in the working layer


  • Too dry or acidic – Add water/lime. If your worm farm is on legs, place each leg in a container of water to stop such pests from getting in

Food rotting and not eaten

  • Too much food/ wrong food/ pieces too big – Add less food, break into small pieces

No worm-tea

  • Not enough water – Add water

Types of worm bins

There are different types of worm bins, but most have a number of layers. Note that it is easier to harvest worm casts from bins which have more shallow layers. The bins to the right are easily available.


  • Add worms and food scraps to the first working tray (level 2), which includes a vented lid
  • Add more levels once the first working tray has filled with casts
  • Fly and pest proof, it stands on 5 legs
  • The tray system allows easy removal of worm casts without getting dirty hands
  • Liquid fertiliser can be removed from the collector tray by using the tap
  • Made from recycled plastic

Dimensions – Diameter 51cm and Height 74cm

Auckland Region Stockists

Worm bins

Worm bins can be purchased from your local garden or hardware store.


Kaipatiki Project 09 482 1172 (Auckland only)
Kiwi Earthworm Distributors (Matakana) – 0800 539 676
Natural Waste Solutions / WormsRus – 0508 967 677

Make your own worm binYou can easily make a worm bin out of large buckets, polystyrene trays or an old bath.If you use a bath, remove the plug. If you want to, you could build a frame to allow the bath to sit securely at waist height. Bricks, posts or blocks may be used for elevation, and for stability, ie, 100-150mm height (allowing room for the liquid collection container placed beneath plug outlet). The plug outlet end must be no less than a 5 degree fall to the lowest point to achieve adequate drainage. Roofing such as ply or corrugated iron will be needed to shed water and provide protection from summer sun.Place into the base of the bath 1.5m of 65mm perforated drainage pipe with two layers of old stockings. This seals the ends and covers the perforations which stops the pipe blocking. Add pumice sand or scoria to a depth of 75mm then place shade cloth, doubled over and cut to fit, on top of filtering layer.BeddingA free draining fibrous matured compost is ideal given that it is not going to produce heat. Dampened shredded corrugated cardboard and lunch paper gives increased air availability and reduces the risk of bedding material heating up. You need to water well and leave at least two days. Then check for temperatures over 25 degrees. If there are any unpleasant odours, apply two handfuls of garden lime and mix in. Avoid fresh lawn clippings. As fresh clippings heat up and cook the worms, only apply old lawn clippings.For quick results, 500g-1kg (2000-4000 worms) should be enough for your worm farm to cope with 400gms to 800gms of mixed food waste each day. This volume will increase as the worms multiply. Spread worms on to bedding and spread food scraps in one area rotate feed sites.As the bath fills use garden fork and loosen bedding, this increases air circulation and reduces bedding compaction.To remove the casts, once the worm farm is full (after nine to 18 months), place a plastic sheet or large container next to the bath, and using a garden fork remove the top half of the worms’ bedding. This is undigested food and is where the majority of worms will be. Place this to one side.Remove all casts. Rinse drainage layer thoroughly catching all liquid.Replace the contents that were put aside and commence the feeding, forking, watering process when required.Your bath worm farm will ultimately digest about 1-2 litres of mixed organic waste a day.