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Wonderful worms

Build your own worm composter


Worm composting is a fantastic way of recycling all those
vegetable scraps, banana skins and tea bags from your kitchen!

A worm bin is a container housing a colony of special worms, known as Brandlings, Tiger Worms or Redworms. Worm bins are ideal for households with small or no gardens, as they produce a small amount of compost and a liquid, which can be used as plant food.

Loads of worms wriggling in a bowl

It's easy and fun to make your own worm composter. Just follow these simple steps, but make sure you get an adult to help you.


You will need:


  • Plastic dustbin. A short fat one is best as it provides a large surface area for the worms to feed. An alternative is to use a rectangular box, the larger the surface area, the better.
  • A drill
  • Sand or gravel
  • Small wooden slats
  • Bedding material for the worms. The contents of an old growbag is ideal, or you could use shredded newspaper or straw
  • A plastic tap. You can buy these from most hardware or garden shops
  • Wire mesh about 20cm square
  • 400 compost worms, available from most fishing shops
  • Wet newspapers


How to make your worm composter:


  • Drill a tap into the bin about 5 - 10cm from the bottom. Don't put it too far up the bin otherwise it won't work properly
  • Place the piece of wire mesh inside the bottom of the bin so that it covers the inside of the tap. This will help to prevent the tap getting blocked
  • Drill some breathing holes into the bin lid for the worms to breathe
  • Place 5 - 10cm of sand or gravel at the bottom of the bin for drainage
  • Place the wooden slats on top of the sand or gravel. The purpose of these is to separate the drainage material from the compost you are going to produce
  • On top of the wooden slats, put down 10 - 15cm of damp bedding material for the worms
  • Dig a small hollow in the bedding material and place the worms inside.


Handful of worms in compost


Feeding and looking after your worms:

  • Ensure the container you are using to collect food for the wormery has a lid to stop flies laying eggs
  • Always make sure the food scraps are chopped into small pieces (smaller pieces are best for your worms)
  • Bury small batches of food in the bedding, slightly under the surface. Make sure you spread the patches around the bin rather than putting them all in one area
  • Place a thick sheet of wet newspapers over the surface to keep the light out and moisture in
  • Only add more food when the worms have finished the last lot. Never overfeed your worms! If you do, the food will rot, upsetting the worms and making nasty smells!
  • You can keep your worm bin outside, but in winter the worms will be warmer (and hungrier) if you keep them inside a garage or shed.


What can I put in my worm compost bin?


WORMS LIKE (Happy, smiling worms)

Yes please:

- Coffee grounds and tea bags
- Fruit
- Vegetable peelings
- Cereals
- Annual weeds (not seed heads)
- Bread
- Green leaves
- Cow/horse manure

WORMS DON'T LIKE (Grumpy looking worms)

No thank you:

- Meat and fish
- Cheese
- Baked beans
- Rice or pasta
- Cooked potatoes
- Grass in any quantity
- Weed seeds
- Diseased plant material
- Cat or dog poo
(as these can contain human parasites)


Collecting your compost


  • After a few weeks you should be able to collect some liquid through the tap, which you can use to feed for your plants. The liquid will be strong so dilute it with 10 parts water before adding it to your plants.
  • After a few months you can empty the bin and use the compost in the garden, then put the worms back and start again!


Your worm composting problems solved:

I have lots of tiny flies in my worm bin.
Is this a health risk?

No. These are probably fruit flies, which commonly occur on rotting fruit and vegetables. These do not harm the compost. A tight fitting lid will help to exclude them. Also, if you bury the vegetable waste as you add it, or keep it covered with damp newspaper, they are less likely to be a problem. Also, it is important to keep the material that you are going to add to the wormery in a covered container whilst it is waiting to go in.

I have tiny white worms in my  compost.
Are they a problem?

These are probably pot worms (enchytraeids), which you will find in most worm bins. They do a similar job to Brandling worms and are nothing to worry about. They are very tolerant of waterlogged or acid conditions so, if you find them multiplying, and your own worms are getting fewer, improve the drainage. Mixing in some shredded newspaper will help. You can also add a sprinkling of calcified seaweed or rock limestone (dolomite) to correct the acidity.

Newly hatched Brandling worms are also whitish and only half an inch long. You can distinguish them from pot worms by their blood vessel, which gives them a pinkish tinge.


worm crawling through apples

I opened my worm bin to find hundreds of worms around the lid. Why?

Either they have run out of food or the conditions in the bin have become unsuitable for them.

Worms hate waterlogged, acidic compost. Piling in a thick layer of kitchen waste so that it begins to rot and exclude the air will cause this sort of problem. Adding fresh green materials that heat up as they decompose will also kill worms or drive them away. Plastic worm bins do not always allow enough drainage from the compost so make sure that liquids are not collecting in the bottom of the bin and flooding the compost.

Worms around the lid of the bin can also be the result of changes in air pressure as worms are sensitive to this.

I am going on holiday. Will my worms die if they are not fed?

An established worm bin can be left for up to four weeks with no adverse effects if you feed the worms well before you leave. If left for longer periods than this, the worm population will slowly decline.

The contents of my worm bin are mouldy. Am I doing something wrong?

Mouldy food is not great for worms as when food rots it heats up. Although this can be good in a compost bin (in which the heat kills off bacteria allowing minibeasts to move in), in a wormery it can kill off the worms, as they have nowhere else to go.

To avoid food in a wormery going mouldy it is best to chop it up small and feed the worms often but with small amounts. Mixing the waste into the bedding with a small fork can also help.