Meet our Three-Bin Home Composting System

Compost, rich in organic matter, is one of the essential building blocks of good soil. It helps retain moisture and adds nutrients as well as binding mineral particles into a lovely crumb structure. It’s great to add to sandy soils to help them clump together, and clay soils to help them break down. Or any soil, for that matter, to improve its overall condition.

Making compost at home is incredibly easy. Not all of us have room for the sort of multi-bay composting setups that Monty Don or Charles Dowding have access to, but the good news is you don’t need a huge amount of space to run a really efficient composting system.

Having experimented over the past few years, I can highly recommend a rotation system using either two or three of the standard black compost bins. They’re available from most DIY stores and garden centres, but you should definitely check online with GetComposting.com to see if your local authority has a subsidy scheme that could get you a couple of standard bins at a very good price.

We have enough room in the utility corner behind our shed for a three-bin setup. The two bins on the right at the ‘current’ and ‘resting’ bins. The ‘current’ bin is the one we’re adding new material to at the moment. They’re open-bottomed, placed on bare soil (or in our case, sand) to allow worms and other organisms easy access to the contents. They’re technically ‘cold’ bins, as they’re not insulated to retain internal heat (like the pricier but more efficient HotBin composter), but they are sited in a spot that catches the sun (as you can see) so they do heat up pretty quickly on a warm day.

There’s a vast amount of information and advice available as to the right mix of nitrogen rich ‘green’ (living or recently-deceased plant matter) and carbon-rich ‘brown’ (long-dead plants, cardboard, paper that isn’t too glossy or heavily inked) material to add your your compost. The RHS advice page on composting suggests a 25% – 50% ratio of greens topped up with browns.

We add all our kitchen peelings, including eggshells, and garden clippings, but not perennial weed roots¹ or potato tubers, as well as the contents of our shredder, ripped up egg-boxes and cardboard tubes, along with regular sluices of water. We aim for a 50/50 mix, but it probably skews towards green due to the large amounts of veg trimmings we produce, even though we’re just cooking for the two of us.

The ‘current’ bin is gradually filled over the course of a year. Then it becomes the ‘resting’ bin for the next year. Nothing new is added to the ‘resting’ bin, and the mix is checked monthly, to make sure it’s moist enough and to give it a good stir around with the garden fork to get plenty of air in.

The switch-over between the two happens any time between now and the end of April, whenever I can find the time to scoop out last year’s compost and bag it up until it’s ready to use on the garden. I started on the job yesterday, and this is the sort of thing I found at the bottom of the bin:

As you can see, everything has broken down quite nicely over the past 12 months, into a dark, crumbly, odour-less mix that will make a great soil improver. There are a few clumps of egg-shell that haven’t fully disintegrated yet, but they can be plucked out and dropped back into the newly-designated ‘resting’ bin before the lid goes on for 12 months.

I think there’s between 120 and 150 litres of compost in just the one bin. Whilst that might not represent a huge monetary saving over bought compost, it’s still the value of a couple of potted up perennials or a few packets of seeds. So in terms of the return on the cost of the initial investment in plastic bins, I’d reckon it will pay for itself in around three or four years.

The third, left-hand, bin is for woody waste: tougher plant stems, clumps of grass, anything that you know will take a longer time to break down. This bin will be left to do its thing for at least three years, allowing as much time as possible for the thicker plant material to break down. At the end of three years the contents will be scooped out and sieved. Any usable compost will be extracted and the rest of the material will go back in the bin for further decomposition.

The main advantage of running two bins side-by-side is that you can ensure a full breakdown of the contents of the ‘resting’ bin over the course of twelve months – especially if you switch at the start of Spring, to really get the temperature up over the summer – without the problem of having to add fresh new material on top of the compost you’re trying to extract from the bottom. That’s always a messy, smelly way to do things, not really recommended if you can avoid it. And you can manage perfectly well without the third bin, but you may have to spend a bit more time picking woody chunks out of your ‘resting’ bin at switch-over time.

Finally, a quick pro-tip re: tea-bags. It’s very tempting to assume that they’re entirely biodegradable, but experience – and much sieving – has taught me that’s not the case, as many tea-bags contain artificial fibres. I’d rather not spend extra time picking chunks of half-rotted bag out of the finished compost before it can be used, so instead I invest a smaller amount of time in splitting the tea-bags open and collecting the spent tea leaves before they go in the compost:

I dump them in the sink to rinse, then squeeze them out and leave them to dry in a dish on the side before ripping them open when they’re reasonably dry. It doesn’t take too long to do – you can always split a few while you’re waiting for the kettle to boil or your next cuppa to brew – and it’s a lot less fiddly than all that picking-out.

Either that or you could always drink more loose leaf tea, which always seems to taste better anyway.

What are your experiences with composting at home? Do you have any suggested improvements on the way we’re doing things? Please do let me know via the comments, below.

Additional Links

¹ Kevin at epicgardening.com subsequently got in touch (Nov ’17) to point me at an article on his site on composting weeds, if you’re interested in trying a method or two.