The trial heaps were

• a standard, slatted, wooden bin bought from a large DIY chain store, with a volume of 0.75 cubic metre (26 cu.ft)

• a typical, local authority plastic bin, of 0.3 cubic metre (11 cu.ft)

• an open heap, also sized about 0.3 cubic metre (11 cu.ft)

All contained the same mix of typical garden waste: large, woody material was chipped and smaller material was shredded. The trial was started in late autumn: although the weather at this time is too cold to be ideal for compost-making, it is one of the few times that many gardeners will have a large quantity of waste material available.

The trial heaps were compared with the main heap at the RHS Garden, Wisley, which is enormous – at least 30 cubic metres (1,060 cu.ft). Despite air temperatures below 10°C (50°F), the temperature of this heap quickly rose to around 70°C (158°F). After two weeks, the heap was turned and the cold air admitted briefly reduced its temperature to below 50°C (122°F). But it was soon back up to over 60°C (140°F) again, and remained above 50°C, with monthly turning, for several months.

No such luck for the trial heaps. None ever achieved more than a few degrees above air temperature, with or without turning. Probably because of its larger size and better insulation, the wooden bin was the best of a bad bunch, and the plastic bin was slightly warmer than the open heap. Crucially however, none got anywhere near a temperature that would kill disease pathogens or weed seeds. So much for the bad news.