A compost heap left alone through autumn cools from the outside in, and the raw material at the edges never quite breaks down. Turning it now moves that unrotted material into the hot centre, and a barrow-load of grass clippings or manure gives the bacteria something fresh to work on before the cold slows them right down. A compost thermometer takes the guesswork out of whether the heap is still cooking or has already stalled for the year.

Turn and Check a Compost Heap Before Winter Sets In

What you need

1 wheelbarrow load grass clippings, comfrey leaves, or fresh manure whatever high-nitrogen material is easiest to get a barrow of
1 old carpet, doubled tarpaulin, or a bin lid to keep rain out and heat in over winter
1 cardboard or dry leaves only needed if the heap turns out sodden rather than warm, to mix through and open it up

Step by step

Pull back the cover and fork the outer, cooler crust of the heap into the middle, so material that hasn't broken down gets a turn at the hot core.
15 min
Break up any compacted, slimy clumps as you go. If the heap feels cold and heavy rather than warm and crumbly, mix in the barrow-load of grass clippings or manure to restart it.
15 min
Push the compost thermometer into the centre of the reformed heap and read it after a minute or two: 40 to 60 degrees Celsius means it is still cooking, under 20 degrees means it has stalled for the year and that is fine this late in the season.
5 min
Firm the heap down, round off the top so rain sheds rather than soaks in, and put the cover back over it.
10 min

Afterwards

Wipe the thermometer clean before you put it away, so it isn't left corroding in a damp shed all winter. Check the heap again in a month: if it has slumped and stopped steaming, that's normal for the season, and it will pick back up on its own once the weather warms rather than needing another turn now.

Questions

Do I need to turn it again before spring?

Not usually. Most heaps are left alone once the weather turns cold and are given their next proper turn when things warm up and the bacteria get going again.

The thermometer read over 70 degrees Celsius — is that a problem?

It just means the heap is working hard, which is normal in a fresh, well-mixed pile. It only becomes a concern in a very dry, densely packed heap, which can smoulder; if you smell smoke or see it, spread the material out to cool it.

Can I still add kitchen scraps over winter?

Yes, but bury them into the centre of the heap rather than laying them on top, where they will sit undigested and are more likely to attract rodents.