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Wonderful worms

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 limited quantity of compost and a liquid, which forms a concentrated plant food.

Loads of worms wriggling in a bowl

You can buy a worm composter from the suppliers listed at the bottom of the page but it's also easy and fun to make your own. Just follow these simple steps but make sure that you get an adult to help you.

You will need

  • Plastic dustbin. A short fat one is better than a tall thin one as it provides a greater surface area for the worms to feed. An alternative is to use a rectangular box, the larger the surface area, the better.
  • a drill
  • some sand or gravel
  • some 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 20 cm square
  • 400 compost worms. These are often called brandlings, tiger worms or redworms and are available from most fishing shops or from the suppliers and worm bin manufacturers listed at the bottom of this page.
  • wet newspapers

How to make your worm composter

1. Drill a tap into the bin about 5 to 10cm from the bottom. Don't put it too far up the bin otherwise it won't work properly.

2. 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.

3. Drill some breathing holes into the bin lid.

4. Place 5 to 10 cm of sand or gravel at the bottom of the bin for drainage.

5. 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.

6. On top of the wooden slats, put down 10 to 15 cm of damp bedding material for the worms.

7. Dig a small hollow in the bedding material and place the worms inside.

Handful of worms in compost

Feeding and looking after the worms

1. Ensure that the container you are using to collect food for the wormery has a lid. If there is no lid, flies will lay their eggs on the food and the eggs will hatch out once inside the wormery. Always make sure that the food scraps are chopped up well.

2. Bury small batches of food scraps in the bedding, slightly under the surface. Make sure that you spread the patches around the bin rather than putting them all in one area.

3. Place a thick sheet of wet newspapers over the surface to keep the light out and moisture in.

4. Only add more food when the worms have finished the last lot. The speed at which the food is processed will depend on the number of worms, the time of year and the type of food added. Never overfeed the worms as, if you do, the food will just rot, upsetting the worms and making nasty smells!

5. 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)

coffee grounds and tea bags
vegetable peelings
annual weeds (not seed heads)
green leaves
cow/horse manure

WORMS DON'T LIKE (Grumpy looking worms)

meat and fish
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

1. After a few weeks you should be able to collect some liquid through the tap, which you can use as a liquid feed for your plants. This will be quite strong so dilute it with 10 parts water before adding it to your plants.

2. 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, although they can be irritating and offensive to some people. 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 masses of tiny white worms in my worm 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 proliferating, 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.

Where to buy a worm bin

If you like the idea of worm compost but don't want to make your own worm bin, there are a variety of worm bins available for sale, complete with 'worm starter kits'. Try the manufacturers and suppliers below:

Wiggly Wigglers

Lower Blakemere, Herefordshire HR2 9PX
Tel: 01981 500391
Fax: 01981 500108

Blackwall Products

10 Glover Way, Parkside, Leeds LS11 5JP
Tel: 0113 201 8000
Fax: 0113 271 3083

Original Organics Ltd

Unit 9, Langlands Business Park, Uffculme, Cullompton, Devon EX15 3DA
Tel: 01884 841 515
Fax : 01884 841 717

Recycle Works

Tel : 01200 440 600

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