Worm farming

Mangakahia Area School and their worm farm.Mangakahia Area School students show their worm farm piled with food scraps.  More and more Northland schools are farming worms. From Kaitaia to Kaiwaka, schools are using all sorts of containers and systems to make friends with wiggly worms.

While kids are in classrooms, worms are hard at work turning waste into something more valuable.

Kaikohe West School, Ohaeawai School, Mangakahia Area School, Pakaraka School, Morningside School, Kaurihohore School, Kerikeri High School – these are just a tiny handful of Northland schools with worm farms.







Why do they do it?

Wiggly worms play a vital role in our environment!

They eat and eat and eat, turning waste into something wonderful called compost. And one earthworm and its offspring can breed 1500 worms in one year. In the right conditions they’ll eat their own weight in food every day!

Student prepares food for the school's "wormhouse'.Midge Ashby of Pakaraka School prepares food for the school’s "Wormhouse".Making a worm farm is one way you and your class can help the environment around you. It’s also a fascinating way of learning about these tiny workers, which burrow away in the soil under our feet.

Worms might be small but they’re important because they eat organic material and soil and make it into humus or topsoil in which plants grow best.

Special types of worms are needed for worm farms. These are not usually the ones found in the garden.

Two types of composting worms are the red worm (Lumbricus rubellus) and tiger worm (Eisenia foetida).

The red worm prefers the top five centimetres of soil, especially where there are lots of dead leaves on the ground. Earthworms found in cowpats and horse manure are almost always these red worms.

The tiger worm has red and yellow stripes on its body and prefers to work in surface areas under rotting vegetation, manure and in compost. They often wriggle vigorously when they are in your hand.

According to the book, Earthworms in New Zealand, there are 192 species of earthworms in New Zealand. Most of these are native species.

However, only about eight species have a major role in improving our pastures, horticultural land and gardens. These are all introduced species. The native worms prefer the native bush where they have grown to love their special habitats.

The other species are earthworkers, which are able to burrow deep in dry conditions. They are better equipped to survive in the sometimes harsh conditions in the soil and garden. Composting worms will not survive for long in the soil unless the conditions are right. They need manure, organic material, moisture and oxygen.
If these are provided, they are very quick to breed and produce a lot of castings, which are great for the garden.

Worms help to increase the amount of air and water in soil. They help to "turn" the soil by taking down organic matter from the top and mixing it with the soil below. Their burrowing creates natural drainage systems. The presence of worms shows the soil is healthy. Worms can compost rubbish faster than any other type of composting method.



About worms

What do you know about worms?

Compost filled with worms at Kaourihohore Primary school.Compost filled with worms busy breaking down organic matter from a worm bin at Kaurihohore Primary School.  The body of an earthworm is made up of rings or segments. These segments shrink and stretch to help worms move through the ground. They do not have eyes, ears or legs. They have five hearts.

The main body parts are the mouth, head end, tail end, saddle and bristles. Setae (bristles) are tiny hairs that cover each segment to give the earthworm grip as it slides forward. Earthworms are composed mostly of water and have no bones. They use muscles to contract the different segments of the body and move along.

Earthworms take soil and organic material in through their mouth. The material passes through the body and emerges through an opening in the tail end as castings. These make great fertiliser.







Morningside primary school develop plans for their worm farm.Northland Regional Council Education Officer Susan Botting helps students at Morningside Primary School, Whangarei, develop plans for their worm farm.  Worms are hermaphrodites, which means they have both male and female reproductive organs. One earthworm and its offspring can build a population of 1000 to 1500 earthworms within a year, according to Earthworms in New Zealand.

The skin of an earthworm is very sensitive to sunlight. Earthworms breathe through their skin so they must stay moist and out of direct heat or light.

If an earthworm loses part of its body, it is sometimes possible to regrow its tail if less then a third of the rear end has been cut.







Council’s role and policies

Morningside Primary students.Morningside Primary School students with plans for their worm farm to be made in some recycled baths.

The Northland Regional Council is responsible for the sustainable management of the environment in our region. One important way the Council can help to achieve this goal is by encouraging the people of Northland to take a more active part in managing the environment.

Worm farming is one way students can do this. They can learn about how they can take action to make a difference by reducing the amount of rubbish being sent to landfills through recycling waste. Worms work to turn rubbish into compost or fertiliser. They also create more worms while they’re at it, enabling more worm farms to be set up.

All this helps the Council in its aims to see wastes managed and minimised to prevent harmful levels of contamination of land, water and air.





How to make a home for worms

There are lots of ways to set up a worm farm.

One way is to build or obtain a wood or plastic bin. Drill holes in two sides and on the bottom. Use a piece of flat wood or plastic sheet to cover the bin.

Moisten shredded newspaper or corrugated cardboard with water, add one or two handfuls of topsoil or coconut fibre and place in the bottom. Sprinkle in some eggshells. Place worms in the box. Worms need time to settle in, increase their numbers and eat their way through the feast you're providing, so in the first 2-3 months, hold back on the food.

When feeding the worms, the smaller the food bits the better so cut it up.  Feed the worms in strips, tomorrow's food placed next to today's and so on. When you keep putting food on top of the last lot of food, there is a good chance it will turn putrid before the worms have a chance to get to it.

Damp old carpet, towels or hessian can be really useful to lie on top of the worms to keep them cosy. This provides welcome darkness for the wrigglers and helps them keep their cool.

The worm bedding should be changed every three to six months. Remove newly made compost and replace with newspaper strips.

When the worms have finished eating the available food and converted it into castings, tip the compost, worms and any newspaper scraps on to the garden.

Worm farms shouldn’t be too wet, neither should they be too dry. Find a local expert in your community to help you get the conditions right. Experiment if you don’t quite get it right first time. 


What do worms like to eat?

Worm food.Mmmm… yummy worm food. Well, the worms like to eat it!Earthworms will eat anything organic – that comes from nature – as long as it can be broken down and is kept damp. They cannot eat dry food.

Worms will eat newspaper, cardboard, compost, dead leaves, crushed egg shells, vacuum cleaner dust, rolled oats, weeds, lawn clippings, peat moss, coconut fibre, carpet or underfelt. Other ideas for worm food are waste from vegetable juicers, soaked and ripped pizza boxes, paper, tissues, dirt, hair, cardboard fast food packaging, potato peelings, apple cores and pea pods.

Composted animal manures are a great food source for earthworms. However, chicken manure should be avoided because it is too strong.

Earthworms also like to eat vegetable or fruit scraps. It is best if the food is in small pieces.

Think carefully about how big your worm farm has to be so you can get the right balance between the number of worms and the quantity of food you’ve got to feed them. Too much and there’ll be clumps of rotting food the worms can’t keep up with. Too little and they’ll starve.

Worms don’t particularly like acidic foods such as oranges, lemons, grapefruit, tomatoes and strong-smelling foods such as onions and garlic. They don’t like the smell and they’ll climb out of their compost bin to get away from it. It is best not to give them meat scraps or dairy products, as the compost bin is likely to become smelly and attract rats and mice.

Some other things that definitely don't belong in a worm farm are plastic bags, bottle caps, rubber bands, sponges, aluminium foil and glass.

How much do they eat?

In the right conditions, earthworms can eat their own weight in food every day. For example, 1kg of earthworms can eat 1kg of food every day.

It is important to calculate how much food is needed in a compost bin. If there is too much food for the earthworms to eat, the compost bin will become smelly. The worms will not be able to process the food before it starts to rot. 

What happens next?


Hand holding worm waste.Worm poo is vermicastings, shown above, which makes great fertiliser for the garden. Food in – compost out! Once the worms have gobbled through the food scraps, they process them into worm poo or castings. There are two byproducts from a worm farm – vermicasts and liquid "worm tea".

Vermicasts are a high quality soil conditioner and can be added to the garden or pot plants.

Worm tea is the liquid waste from the worms. It’s not for drinking! Worm tea is also a good fertiliser and can be sprayed on plants and vegies to give them a boost, and protect them from diseases and bugs. 

Use diluted at a rate of one part liquid to 10 parts water.






How many worms will we get?

Given ideal conditions, enough food, and lots and lots of worm bins, two adult worms, and their children's children, and their children, etc, can produce more than one thousand worms in one year.

Handful of worms.A big handful of very wiggly worms.Each adult worm can mate roughly once every 10 days, and from that mating, each of the worms can produce usually one, but sometimes two "cocoons". Each of those cocoons can hold anywhere from 1 to 20 baby worms (spawn), though they usually average out to four which hatch out successfully.

However, there is no need to worry about worms taking over the school. Worms will restrict their breeding to match the available food and size of their enclosure. Most vermiculturists (worm breeders) assume an average increase in population of 100% every 4-6 months. That means that if you start with 100,000 worms, you’ll end up with 200,000 four to six months later. But as long as worms are kept in the same sized container (remember to keep the bedding fresh by changing it every few months), you don't have to worry about having too many worms. Most worms probably live and die within the same year, although sometimes they can live longer. 





Take care with health

Students should be careful when dealing with food scraps and manure. Diseases can be present in soil and compost, and can infect any cuts or breaks in the skin on hands. Manure should always be well composted before being added to a worm farm to reduce risk to students. Make sure hands are washed afterwards, or that students wear gloves.


Worms at school

Students from Kaurihohore with their worm farm.Students from Kaurihohore Primary School north of Whangarei with their worm farm built in an old shower tub. Schools which have successfully made worm farms often have a lot of good advice built up through trial and error. If you want to try making a worm farm, contact one of the other Northland schools mentioned in this document and find out how they did it or find out if school near you is farming worms.

One school started with 1kg of worms. The main focus was to feed them up quickly so that they could get them reproducing, to increase a waste consumption. The students have found chopping the worm food in a blender has helped a lot. Small pieces of food are easier for the worms to digest. The students add lime dust each time they feed the worms, which helps to break down the acid content. 

The school has bought a proper worm bin called Can O Worms, so they haven't had the trouble of worms drying up. They recommend keeping the bin in a place that only gets a bit of morning sun only, as they don't like it too hot, say above 18 degrees. They have found they don’t have to water them.

Once the worm farm has grown, the school plans to move it out into an old bath that has been raised off the ground. The idea is to let the worm tea drip out of the drainpipe.




Colour coding helps even the youngest students.Colour coding helps even the youngest students at Mangakahia Area School, at Poroti, remember what to put in each bin. Red is for paper, green is for food and blue is for plastic. The yellow bin takes any other type of rubbish.

Put a layer of shingle in the bottom of your bin, cover with weed mat, and place paper, dirt, grass clippings and food on that, then cover. The students say that if the compost smells, then there is too much food and it will rot. If you have fruit flies hanging around the bin, it means the food is too acidic and lime needs to be added. Grass clippings should be left to sit outside for a while so that they cool down, or else it cooks up the bin. This can be a fatal mistake as the worms could overheat and die.

The schools with worm farms collect food in special bins put aside for food scraps, cardboard and paper. A good way to help students remember what each bin is meant to hold is to give them colour codes.

For example, at Mangakahia Area School, classrooms have four bins with different colour codes. Red is for paper, green is for food and blue is for plastic. Yellow bins take any other types of rubbish. Teachers are also role modelling well, and the school is kept neat and tidy as students have learnt to pick up rubbish straight away. The school has made gardens to take the compost created by its worm farm.

This approach is already showing lots of benefits, which include saving the school money. In the first week of 2002 the Mangakahia Area School slashed the amount of rubbish it produced by 20%. In the second week that saving doubled. You can find out more about Mangakahia Area School’s ``Radically Refusing to Rubbish’’ project at the school’s website, www.mangakahia.school.nz.

A recipe used by Kaikohe West school for making a worm farm in a bath is:


  • A layer of coarse scoria in the bottom of the bath.
  • A layer of sand.
  • A layer of fine scoria or stones.


  • Cover with weed mat.
  • Make the worm bedding out of newspaper and a choice of scraps.
  • In go the worms.
  • Cover them slightly and put in a little garden lime.

Setting up and running a worm farm means working through a new experience for many of us. With that comes trying various options and seeing which work best. One Northland school is carrying out a long-term science experiment looking at which worm farming options work best. It’s part of their technology programme too.

So, what can you do if your worm farm’s got a problem? Where might you go to find expert help?

Brainstorm with your class, with your teacher. Maybe a family in your school has already got a worm farm at home and could help. There are the websites and books listed at the end of this document. Try emailing one of the schools above and ask them for advice.

But remember worms are living creatures and looking after them in a way which considers their best welfare is important too.

Action Planner

The hardest part about a project is often the planning stages. One great way to organise a project is to use the action planner on the next page. It’s an easy way to sort out the different parts of a project.

Start with your vision or problem at the top of the action planner. One part of the action planner to spend a fair bit of time on is named, ``What are we going to do?’’ Brainstorm for ideas. You will be amazed what can come up. Once this has been worked through, you can assign each of the members of your group or class with a task. Planning properly will give your projects much more chance of success.
Try using this action planner in your classroom, your school, at home and in other areas of your own life.

Action planner.

Funny facts about worms

  • The largest earthworm ever found was in South Africa and measured 6.7 metres.
  • Worms can grow a new tail, but not a new head.
  • Baby worms hatch from cocoons smaller than a grain of rice.
  • Worms can eat their weight in food each day.
  • If a worm’s skin dries out, it will die.
  • In one hectare of land, there can be more than 2.5 million worms.

Further information

Check out this great wormy website:



Sources: Northland Regional Council Education Officer Susan Botting; Mangakahia Area School; Kaurihohore Primary School; Morningside Primary School; Pakaraka Primary School; Earth Worms in New Zealand, Life Beneath the Surface; Earthworms an integrated activity package; Environment Canterbury; Earthworms activity package, Carmel Breman, Auckland College of Education; Squirmy Worms website; Worm Farm website.