It's getting hot in here

For many gardeners, the word composting conjures up images of hot, steamy piles of organic matter that often smell strongly of ammonia gas. This is a classical “hot” compost heap.

- ANGUS STEWART

Hot composting happens when the environment in a pile of organic material is ideal for heat-loving microbes to thrive and multiply in exponential fashion (scientifically this group is known as “thermophiles”). Under ideal conditions for this fascinating group of microbes, the temperature can build up to 80°C. If the whole heap remains that hot for at least several days to several weeks, the payoff for gardeners is that those conditions will be sufficient to kill virtually any weed or plant disease present. Indeed, this is what happens with industrial-scale composting of municipal green waste collections. So if you don’t have the space or energy to do your own hot compost heap, then your green waste bin (if you have one) provides a great alternative to ensuring your organic waste will be composted in an environmentally friendly way. “Hot” composting is a wonderful idea as it allows you to decompose virtually any organic material including meat scraps and persistent perennial weeds such as couch grass, onion weed and oxalis.

A successful hot compost heap can reach maturity and be ready to use in the garden in the space of a month. However, this does require regular turning of the heap (every few days) and attention to moisture levels to ensure every part of the heap reaches temperatures high enough to ensure the whole mass is fully broken down.