How to make a worm bin

This simple outdoor worm bin is made from recycled materials and is designed to take all your food scraps, including cooked food and even meat! Here's how to make a worm bin!

This simple outdoor worm bin is made from recycled materials and is designed to take all your food scraps, including cooked food and even meat! Here’s how to make a worm bin!

By Marit Parker

Making a worm bin is easy, if you start by looking at it from a worm’s perspective. Worms like to be warm, but not too hot, and damp, but not too wet. They will eat almost anything, turning it into the most beautiful compost. In fact, worms are central in any garden, whether you have a worm bin or not.

A worm bin doesn’t have to be expensive. This one costs nothing at all. You don’t even have to buy any worms. “If you build it, they will come” is especially true of worms,who seem to have a sixth sense for a new source of food, and quickly send word out to their mates when there’s a feast.

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Just a few of the worms that have already moved in to a new worm bin

As well as catering for worms needs, this worm bin is designed to exclude rats. This is done in the first place by placing a metal grid on the ground where you want your new worm bin to go. This can be made from the shelves of an old fridge (call into your local recycling centre and take a peek at the fridges awaiting collection) wired together to stop determined rats making a way through.

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Next, put a tyre on top of the this grid. Tyres are available at any tyre centre and most garages, where they are a waste problem. Worms love them because they hold in both the warmth and the moisture. They can be stacked three, sometimes four, high without needing any supports, and no rat can eat through a tyre!

Finally, find a lid. A piece of wood, such as an old door from a kitchen unit, is perfect. Make sure it’s big enough to sit on the rim of the tyre all the way round. Then weigh it down with a brick.

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To start using your worm bin, I recommend putting a little cardboard in the bottom of the bin. Worms love cardboard and this will quickly attract your first worms. Then just start adding your vegetable peelings and food scraps. Because this bin is rat proof, it is safe to add cooked food and even meat.

Things to avoid

Because the worms can come and go through the grid at the bottom, you are unlikely to harm the worms. If they don’t like your latest offering, they can go elsewhere.

One thing worms definitely dislike is citrus fruits, but there is a simple trick that can solve this one. If you have squeezed a lemon or some oranges, put the skins in your washing up bowl for one or two washes first. The citric acid will help cut through the grease, and the oils will smell good in the steam. After that, they are fine in the worm bin.

Where to put the worm bin

A worm bin that is near the kitchen door is more likely to be used regularly. A spot out of the wind is a bonus, but the tyres mean the inside of the bin is always sheltered.

A big advantage of this design is that it is not permanent. When your first bin is full, you can make another one in a different spot. I like to site my bins where I need some compost. When the worms have done their work, I simply move the tyres, lid and grid to another place, spreading the compost where it is, or scooping it into pots nearby.

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Stray bits of plastic – and teaspoons! – can be fished out at this stage

How many worms bins do I need?

This will depend on how much you have to fill the bins, and what your climate is. I live in a temperate climate, and the speed the worms munch away here means I usually have three, sometime four, bins on the go: the one I am currently using, the one that has just been filled, and one where the compost is almost ready.

What do I do if it freezes, or if there’s a heatwave?

Nothing! Because the worms can get in and out freely at the bottom, if it’s too hot or too cold in the worm bin, they will find somewhere else until the weather improves. Don’t forget the tyres insulate the inside so the worm bins are protected to a large extent from changes in temperature. They also hold the moisture, so even when it hasn’t rained for a long time, they will remain damp inside, and of course the food scraps you add will bring in some moisture.

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Worm compost, made in situ, ready for planting

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