On the left is a build as you go cold compost pile and on the right is a hot compost pile that you can build in one go
What is cold composting?
Cold Composting is very similar to hot composting, the difference being with a cold heap you are making it gradually as materials become available. Every few days adding a bit more. With a hot heap you’re making it all in one go.
Check out the hot composting section for more info on compost structures/siting. The same principles we talked about in the hot composting section are applied to cold composting. The mixing of greens (nitrogen rich materials like grass, food scraps, manure etc) and browns (carbon rich materials like straw, leaves, cardboard etc)
The principle here is that over time, you put some green into your compost heap add a similar amount of brown.
Top tips to remember:
- Keep up the moisture levels.
- Aerate from time to time
- Add varied compost ingredients, the more, the better!
- Add some tiger worms, this will speed up the whole process!
Example 1
Adding food scraps every two to three days on to the heap. Cover or mix in some browns in this case some old dry grass/garden clippings etc. Cover heap with an old piece of carpet or cardboard.
Example 2
Lawn is mowed producing three to four catchers full of clippings. Rather than dump the whole lot on to the heap look at layering 5 -10 cm layers with straw. Even better mix in a layer of manure (often available for sale on roadsides) into the heap. Remember green, brown, green, brown, green, brown etc. Don’t forget to sprinkle some water as you go.
Example 3
Just purchased four bags of manure from the side of the road. Options here are:
- add to your heap interlayering with straw
- save the bags to use when adding other materials to the heap eg a mass of lawn clippings
From the three examples above you can see its a good idea to have some materials stored on the side ready to use- like straw/dry grass/shredded cardboard/manure.
When the heap is of a good size (approx a metre high) cover it up and leave it to mature. This is going to take six months to a year. Check its moisture levels from time to time, paying attention to the edges. To speed up the process aerate the heap from time to time using a garden fork or an aerator tool.
This style of composting is a lot slower than if you made a compost pile in one hit. Check out the hot composting page for this.