top of page

Composting III Composting with Worms

Updated: May 15, 2020

It is true that the littlest of creatures make the biggest of impacts on human society. In a time of global pandemics, it is worth remembering that an insect 2.5 millimetres long - Xenopsylla cheopis – or the Oriental Rat Flea was responsible for the deaths of one-third of the human population in the fourteenth century. Bubonic plague still makes periodic comebacks to this day.

A much more beneficial organism to human development is Apis mellifera, or the Western Honeybee. Bees are the single most important pollinator for agriculture globally - pollinating 80% of all plant life. In other words, most of the food on your plate and a lot of the clothes on your back. However, globally bee numbers are dwindling – which could have a significant effect on human development, so it’s down to us to help them out.

There are ways in which we can prepare our gardens to attract bees, encouraging them to pollinate all the year through and in later posts I’ll explain how you can attract pollinators to your garden by raising native wildflowers and bee-friendly plants.

However, today I’m going to talk about that other garden-dwelling invertebrate that has had a huge impact on the human development – the earthworm – and how it can help you out in your garden.

To begin with, a worm is not just a worm. Earthworms are classified into three main categories: worms you find in leaf litter or compost, that are nonburrowing, live close to the surface and eat decomposing organic matter; Topsoil-dwelling worms that feed, burrow and cast within the soil, creating horizontal burrows in the upper 10cm to 30cm of soil; and worms that construct permanent deep vertical burrows, which they use to visit the surface to obtain plant material for food, such as dead leaves.

As gardeners we love all three types, as all of them bring major benefits for soil. They convert dead and decaying matter into humus, or the organic component of soil. They add nutrients to the ground by munching the mineral parts of the soil and excreting it in a form that plants can take up for their own growth. And they create channels in underground by their burrowing, which allows air and water access and mix the components of the soil which are then absorbed by plant life.

To continue my series on composting, today I’m going to talk about composting with worms. Worms – primarily the top-dwelling type – commonly known as bluenose, red and brandling or tiger worms will already be active in your compost heap, but you can create your own specific worm composting system.

Again – like a conventional compost pile – the worm-composter, or wormery comes in different sizes. You can get small caddies that can fit under your kitchen sink. If you live in Tower Hamlets, you can get a subsidised wormery from the Council for just £5.00 (link:, you can order more sophisticated systems online (link:, or try to make your own. I’ll show you a few different systems in an upcoming video.

To start worm-composting, you need a suitable container. The system needs a method of draining, as one of the biproducts from the process is a liquid leachate, which is an amazing organic fertilizer. If you don’t drain this liquid out, your wormy friends will drown. You then need worms. Don’t try and dig for worms, as the ones that you’ll get out of your garden beds will be the wrong type, and not be able to compost. You could pick worms out of your compost pile by hand, but this will take a long time. The quickest way is to order composting worms through the post from a supplier. That way you’ll be able to guarantee quality and quantity. It’s best to start off your system with a few hundred worms. This is the supplier I use (link: The two types you’ll need are Tiger Worms (Eisenia fetida) and Dendrobaena or Bluenose Worms (Eisenia hortensis).

You then have to set up their home. I use a mix of damp, shredded newspaper and coir (or coconut husk – you can buy this from gardening stores and is also great as a material for planting seeds). They’ll need the bedding to be moist, not wet, so squeeze a bit in your hand; if any water drips out, your bedding is too damp. It needs to be moist to the touch, not soggy. After placing the bedding in the base of your container, you can introduce the worms. Leave the system for a few days to allow the worms to get established. They’ll eat the bedding, so don’t worry about them getting hungry. You can then start to add the food.

Worms aren’t really very picky diners. They’ll eat most organic vegetable matter and about half their own body weight a day. In commercial systems they also eat meat, dairy and human excrement – but I wouldn’t recommend you start adding material like this to your system, as it will go off, putrefy and introduce bad pathogens to your system. I’d also advise you avoid cooked food, oils, bread, as this too will putrefy. Finally, try to avoid citrus fruits, as their oils can damage a worm’s skin, as well as garlic cloves and onion. Apart from that everything’s game.

You can use: kitchen scraps, vegetable trimmings, spoiled or rotten fruit, herbs and salad, teabags, coffee grounds, houseplant cuttings and dead flowers, nettles, grass cuttings, cardboard (especially toilet roll cores), paper (receipts, kitchen towel and newspaper), crushed eggshells. I’d advise you chop the material up into small pieces, or even give it a quick blitz in your food processor, as this increases the surface area and the worms eat decaying matter.

You need to add little and often. Worms can only work at the surface of the soil, so a big pile of material will not be accessible and will start to ferment or compost – both of which will kill your worms. As a rule of thumb, if, when you open your wormery you see worms on the surface moving around, you need to feed.

So why do we do this? Well, to start with worms help dispose of our waste in an ecological manner and their guts also grind up nasty pathogens like e.coli and salmonella. In return for eating your waste and scraps, the worms will give you the best compost you can use. Although wormeries take a long time to fill up, underneath the main body of worms will be their manure. This is called a casting and is the crème de la crème of compost. It only needs to be used by the handful, not the barrow-load. The castings are great fertilizer – high in nitrogen, phosphorus and potassium – and will also introduce beneficial microbes into your garden. I use it as a top dressing for my potted plants, window boxes and raised beds. You can also use castings as a foliar feed by putting around 1 to 2 litres of castings in a bucket of 30 litres of water and spray your plants.

The leachate – or liquid you drain from your wormery – is also an excellent liquid feed for your plants, especially fruit and tomatoes. Just dilute the leachate 1:10 to 1:15 with water and use on your plants.

I will give you a guide to harvesting your wormery in a video I’ll publish soon. Composting with worms is great fun, great for the environment and great for your garden. But do look after your worms like you’d look after your pets. Think of the wormery as a mini-farm, not a trash can. I’d love to hear your thoughts or any questions in the comments below.

#gardening #homegrown #compost #growyourown #wormy #composting


bottom of page