Worm farming – compost in small spaces


May is always thought of as composting month, probably because the autumn leaves that fall at this time of year provide valuable bulk for compost. But if you don’t have room for a compost bin, a worm farm is a compact solution that is ideal for even the smallest backyard. Inside the farm, contented compost worms will happily turn kitchen scraps into usable compost.

How to start

You can make your own worm farm using plastic or polystyrene boxes but it’s easier to buy a purpose-made container that will usually have more than one level. Some local councils even sell them to residents at discounted prices. There are numerous designs, most of which have a tap to drain off liquid that can be diluted to use as an organic plant food and soil stimulator.

Start by choosing a position for the worm farm where it won’t get too hot or cold. You may even have to move it around as the weather changes over the year.

Put a few sheets of damp newspaper on the base of the bottom level, then cover with a layer of bedding. Aged horse manure makes good bedding if you can get it. Otherwise use what you can get hold of, including shredded newspaper, shredded egg cartons or old organic mulch. A little bit of soil helps, too. Either add the soil to the bedding or spread a layer on the bottom beforehand. Dampen the bedding layer and add some pieces of vegie scraps (food) so that there’s time for them to be partially broken down before the worms arrive

Next, the worms

The worms that go into the worm farm are not the same as earthworms, so you can’t just pinch some out of the garden. Buy special compost worms – they’re suited to the rich diet they’ll be fed. Spread the worms over the bedding material and they’ll quickly settle in. Cover them with a piece of damp cloth, hessian or an old towel. Put the waterproof lid back on and, once again, check that the site’s not too hot or cold.

Feeding the worms

Compost worms will eat most vegie scraps but it’s best to avoid too much of any one thing. They don’t like really acidic foods – such as onions, citrus and chillis – and it’s better if the food is chopped into smaller pieces beforehand (big lumps will be too much for their tiny jaws!). Egg shells are okay but, again, break these up beforehand. That way, even if the worms don’t eat them, the shells will end up adding extra calcium to the worm castings that are produced. A small amount of Yates Garden Lime every six months or so will help keep everything sweet.

Once the worms have converted a fair amount of the bedding and food into dark, crumbly worm castings, move the castings and bedding to one side and put some fresh bedding and food on the empty side. Or, if you have a farm with multiple layers, start feeding into the layer above and encourage the worms to move up. Then swap the trays.

Use the castings

Add worm castings to the soil, mix in with potting mix or soak castings in water to produce a liquid food. The worm ‘wee’ or liquid that comes out of the farm can also be diluted to the colour of weak tea and used as a fertiliser. It’s not very strong, though, so fast growing plants will need to have other food as well.


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