Compost bins - I love 'em! Except when Clients ignore my very specific instructions on what to put in, and - more importantly - what NOT to put in.
Most of us already know that we don't put perennial weeds such as bindweed, couch grass and ground elder into our compost bins, as they will just continue to grow there: and we know not to put potatoes and tomatoes (or their peel) into the heap, partly for fear of blight, but mostly because if we do, we will have tiny potato and tomato plants popping up wherever we use the compost. And of course we all know that we never put plastic, glass, metal or other non-organic things in there.
But there are other things to avoid, which might surprise you: tea bags, for a start. One of the pictures above is the "bucket of shame" from when I emptied a Client's black plastic "dalek" last week. Quite apart from the mass of tiny slivers of plastic (“As I mentioned last year, please take a little more care when shredding - paper only!”) there was tea bag after tea bag after tea bag... this is just the last half-bucket, by the way, I'd already emptied it three times before I thought to take a photo.
Why do they not rot? Well, if you think about it, they are made of specially treated paper that does not fall apart when put into boiling water, so it shouldn't really surprise you to learn that they don't rot on the compost heap either.
Furthermore, the fabric of the tea-bag contains small amounts of polypropylene which melts when heated, which is how the bags are sealed in the factory. And we don't want plastic on the compost heap. To be honest, I wouldn't really encourage you to tip even loose tea-leaves onto the compost, as they are full of tannin. Likewise coffee grounds – ugh!
Talking of glue, be careful with cardboard as well: corrugated card is stuck together with some noxious stuff which apparently includes heavy metals, so avoid adding it.
And then there is the famous eggshell myth: eggshells contain all sorts of lovely minerals so add them to your compost, say all the books. News flash: they don't rot. Even if you crush them, the bits are still visible in the compost - lovely, when you spread it out on the beds! The second photo shows a nest of eggshells, deep in an otherwise superbly rotted compost heap. As you can see, completely unrotted! And, despite extensive internet research, I have been unable to find any scientific proof that eggshells contain - or, more importantly, release - any nutrients or minerals into the soil. The same goes for the myth that you should water houseplants with the cooled water in which you boiled your eggs so they can have the benefit of all that “goodness”. Who says? There is no proof whatsoever. So don't add eggshells to your compost, unless you like seeing the bits all over the garden later.
I won't bore you all with my views on citrus peel (it doesn't rot!!), ecover packs (they don't rot!), “biodegradable” fabric washing-up cloths (“aargh!”), and finally, my pet hate, corn-starch food waste bags.... but I think you can guess where I stand on those items, too!