Size, heat, air, moisture, plus some additional factors.

The really great thing about a composting bin is what you can put in it; there isn’t much you can’t add to it in fact, with a few notable exceptions.

(Before I continue, I should point out that the accompanying photo is in fact a deformed carrot, very tasty, and definitely won't be going on the heap, at least not the edible parts).

Essential#5, Ingredients: If you think in terms of what can rot down fairly quickly and what can’t, you’re on the right track. Twigs and branches should be avoided as should animal bones (not a good idea as these or any residue meat will encourage vermin).

As to what is good material, I would say that any kitchen waste, old vegetables, peelings, fruit that’s past its best, although watch out for tomato seeds as these are virtually indestructible even withstanding the high temperatures of composting and whilst it’s nice to have a few free tomato plants later on, they can be a nuisance in vast quantities!

I also empty the contents of the vacuum-cleaner straight to the heap. Paper can be added if used sparingly, i.e. not complete editions of The Guardian for instance.

Broken egg-shells can be used as long as they are well crushed or else they’ll come back to haunt you at a later date. N.B.Slugs and snails don’t like egg-shells apparently.

Mower clippings are an excellent, indeed necessary, addition but should be mixed with some course weeds-dandelions, nettles etc. (having been baked in the sun beforehand).

Grass clippings produce a lot of heat (essential#2) when they rot down but if they are not distributed with other stuff will become a nasty, slimy mess.

Men only: You now need to consider what’s known as activation (essential#6). There are many prepared brands of compost activators available if you’re willing to spend your hard-earned cash on them however I happen to know of a much better way to produce an activator that is not exactly free but has its merits in an indirect sort of way.

This product is what the great BBC presenter “Bob Flowerdew” (what a name!) referred to as recycled beer and/or cider and presumably wine. I don’t suppose it really matters what the original intake is and Mr. Flowerdew’s preferred tipple is just to give an example. It’s what comes out that matters.

You will need to obtain a used but cleaned-out 20 litre plastic container with a close-fitting lid into which you relieve yourself (emulsion paint tubs, that sort of thing). Now I’m not being sexist here but I’m afraid it’s only male urine that is acceptable; it’s something in the female hormones apparently.

Once you have half-filled this bucket, it will become evident why a close-fitting lid is advised; it pongs somewhat. That’s the time to add it to your compost heap. It also provides moisture (essential#4). I also suggest a second container like this to keep in the kitchen for your household compost items. It is best to add large-ish quantities to your heap each time rather than piecemeal additions. Think: quantity and size (essential#1)

Worm welcome: Composting is nature’s way of returning good stuff back to her soil and so continuing the cycle but she needs a hand for this in the shape of bacteria, fungus, micro-organisms, invertebrates etc.(essential#7). The ones to watch for in particular are called Brandling Worms. These creatures are pinkish with brown bands and once you have these in your compost, you know you’ve got a good, workable heap. Although you can import them in, say, a shovel of half-rotted horse-manure (also a good activator), they seem to appear miraculously of their own accord which is very good news.

These worms and their lesser and lesser companions will, in no time, chomp away at your unwanted organic material converting it into a rich and fertile additive to your garden.

Apart from your home-made activator, it may be necessary to add a little water (though not too much) from time to time especially if, like some people, you cover your heap with a piece of old carpet to conserve heat.

In conclusion: Now all that remains is to turn your compost after a month or two and this is why you might consider adding another bin to make the job much easier. Turning the compost is crucial as it provides air (essential#3) therefore aiding the breaking-down process.

Well that’s about all for now. You’ll no doubt want to think about a smaller third bin so that you can transfer the stuff that’s ready to use into it. With hope and a degree of patience you won’t have to wait long for this.

In the meantime, if you have been, thanks for reading and happy composting!