I share my house with about 20,000 worms. They live in a Can O Worms wormery composter (see picture). It’s a great composting solution for me because I haven’t got a garden big enough for a compost heap/bin, and because the organic waste I produce is all from cooking (rather than gardening). It’s particularly fabulous that I can keep it indoors (in my utility room) so I don’t even have to go out in the cold or rain to put my fruit and veggie peelings in the compost. And you can put cooked food in it (which you can’t put in a regular composter as it attracts rats). Not that I throw out much cooked food.

My Can O Worms composter in the corner of my utility room

When I got my Can O Worms and started composting for the first time, I was amazed by how much it reduced the waste I sent to landfill.

You can see from the photo that the Can O Worms consists of four layers, covered by a lid. The bottom layer collects liquid (which you drain off using the tap) and the other three layers contain the organic waste (mixed with torn up cardboard). When the top layer is full, you take it apart, empty out the bottom layer (which is now full of rich, dark compost) and put it back together with the now-empty bottom layer becoming the new top layer.

Emptying it is quite a job. The full trays are heavy. Plus I’ve never done it without making a mess of the floor. I clear other stuff out of the utility room first and mop the floor afterwards.

However, it was five months between the most recent time I did it and the time before that. And it’ll probably be longer than that before I need to do it again because summer’s coming and, when the air’s warmer, the waste rots down faster, making room for more.

Here are my tips for happy worm composting.

1. Don’t leave it too long

Don’t wait until the top tray is full to the brim before emptying it. Remember the top tray will become the second tray and the new top tray needs to sit within it. If it’s brimful, the new tray will sit on top and the worms won’t be enclosed. They like to explore so they’ll climb over the side, fall out and expire on the floor.

However, it can be fairly full. The waste in the tray below will have broken down making some space so you can move some of the waste from the new second tray into the new third tray. Plus it seems to work for the new top tray to sit slightly high at first, as the waste in the new second tray soon breaks down and, within a few weeks, the top tray is fully slotted into place.

2. Protect your wormery against the rain

I did encounter a few challenges at first. My Can O Worms was outside for several years (my utility room is a relatively recent addition to my house). It rained heavily not long after I’d first got it and lots of worms got washed into the liquid tray, where they drowned. While it wasn’t enough to stop the Can O Worms being effective, I felt bad about it. I know they’re only worms. Still, though, I feel responsible for their wellbeing.

Even once your wormery is well established, rain is a nuisance as it fills up the liquid tray. If you’re going to keep your composter outside, you might consider getting a raincover for it. (They’re a tight fit by the way. I could just about get one onto my Can O Worms using both hands and one knee! You might want to get someone to help you).

3. Keep your worms cosy

If you’re keeping your wormery outside, and the temperature falls below freezing, wrap your worms up. You don’t have to knit them each an individual worm sock, just tie a large piece of plastic (e.g. bubble wrap) around your wormery. I was lucky enough to find a roll of plastic that someone was chucking out on my street. You could try asking on Freegle/Freecycle.

4. Follow the instructions

I thought I’d be able to get away without adding ripped up cardboard. BIG MISTAKE which resulted in a disgusting smell and an infestation of fruit flies, which took years to die down. Each summer, whenever I lifted the lid, they’d swarm out. They don’t do any harm. They just make putting waste into the compost less pleasant and they tended to get into my kitchen too.

To solve the problem, the first thing I had to do was work loads of ripped up cardboard through the slimy, sludgy mess my organic waste had become. I wore rubber gloves for this task, which helped. It didn’t stop the smell though. Man, it was bad. Bad enough to make me gag.

Moral of the story: follow the advice that comes with your Can O Worms! The flies continued to be a nuisance for years afterwards: until it occurred to me to put cardboard on top of the waste I added each time, instead of the other way around. It’s never smelt bad since by the way.

What it looks like under the lid and moisture mat

5. Make your own moisture mats

Don’t spend money on replacement moisture mats. The moisture mat is a mat of organic matter which sits on top of the top layer of waste/card. It keeps it moist and dark in there, which encourages the worms to come to the surface and eat the freshest waste (which speeds up the composting process). Eventually the worms eat the moisture mat too.  They get through one every six months or so.

You can buy replacement ones made of, for example, hemp. I make my own though. I just cut a circle of fabric out of a worn out piece of clothing, a towel, bed linen etc. You can use anything so long as it’s made purely from organic fibre (e.g. cotton including denim, wool, hemp, linen, flax). You could even use a newspaper or a piece of cardboard. If you make a mistake and put in a worm mat that’s got some inorganic fibre in it (like polyester, nylon or rayon), all that will happen is that the organic fibre will break down and the inorganic material will be left behind. It won’t do any harm.

By using waste material rather than buying a moisture mat, you not only save money, you reduce your environmental impact even further.

6. Don’t accidentally start an allotment in your wormery

I avoid putting in seeds (tomato, pepper/capsicum, butternut squash, orange, lemon) as they sprout. I came back from holiday a few months after I’d got my wormery and lifted the lid to find a small crop of etiolated sprouts fighting their way out. While it doesn’t matter if one or two get in, I put seeds into landfill. Celery bases sprout sometimes too though it doesn’t cause a problem. Apple and pear pips don’t seem to sprout.

7. Other than that, if it’s organic they’ll eat it (mostly)

The booklet that came with my wormery says that the worms will eat foods they prefer first, which means that acidic items like citrus peel and onion skins will take longer to break down. I can’t say I’ve noticed this. What I do find is that some waste, such as tomato skins and avocado skins, doesn’t break down at all, and I no longer put such items in.

I do put in the paper bags that my veg box people put mushrooms and other veg in, empty flour bags, worn out cotton knickers…anything made of paper, card or organic fibres will break down and get eaten.

Watch out for paper items that have layers of plastic in them though (e.g. paper plates, the internal bag of a packet of icing sugar). Not that it’ll do any harm. The plastic just won’t break down so it’ll still be there in your compost when you empty the tray.

8. If you don’t like the muck, wear gloves

I keep a pair of rubber gloves by the composter which I use exclusively for it. Not everyone would bother. I’m sure people who are into gardening and used to digging their hands into earthworm ridden mud wouldn’t feel the need. That’s just not me (I’ll talk about gardening in a later post).

Anyone else out there a worm composting fan? Anyone trying it and having problems? What other composting methods work well for you? What prevents you from composting? Comment below.