Hot composting is a batch process that uses aerobic decomposition to break down organic materials into humus at temperatures over 60°C within 3 weeks. It requires a mix of green materials like food scraps and grass clippings with brown materials like leaves, straw and sawdust. This kills weeds and pathogens. A 3-bin system is recommended where materials are regularly turned into the next bin. Comfrey leaves add nutrients and help the process. Problems can be fixed by adjusting moisture or adding more brown materials. The finished compost is a dark, earthy smelling material that improves soil structure and fertility.

1. Hot composting
Why and how to make it – my
experience

2. Any compost = Lush vegies

3. 3 bin system using chooks

4. Ideas for 3 bin system

5. What is hot composting?
• A batch process: mix it all at once from
material you have collected
• It is free
• Unlike other methods of composting it kills
weed seeds and pathogens
• Can deal with meat, dairy, onion and citrus
scraps

6. Scientific definition
• “An aerobic process of
• fast oxidation which
• breaks raw organic materials into
• humus
• at temperatures of up to 60°C
• within three weeks”

7. What goes in it?
Green and brown
Grass clippings leaves
Coffee grounds straw
Manure sawdust
Kitchen scraps shredded paper
Garden waste Tissues,
cardboard rolls

8. Why hot compost?
• Improves soil structure and adds nutrients
• It is quick. Finished compost in a few weeks
• Higher nutrient content due to less leaching of
nutrients
• Greater volume than cold compost
• Fewer viable weeds and weed seeds (keep out
couch and kikuyu)

9. Dealing with perennial weeds
• Weeds like couch and kikuyu can be either
solarised or drowned.
Either
• put them into heavy black plastic bags and leave
in the sun for several months.
Or
• put them in a bin and cover completely with
water for several months.
The resulting contents can then be composted.

10. How to make hot compost
• One third green
• Two thirds brown
• 3 bin system
• Layer the materials and water each layer well
• Every so often add comfrey leaves or yarrow
• When finished cover the top with damp
newspaper and cover with lid

12. • After 4 days turn into next bin
• After 2 weeks build another pile
• Then regularly turn each of the piles into the
adjacent bins
• You will have a regular supply of compost
depending on how long your materials last
and how diligent you are at collecting

13. Tips and tricks
• Watch out for people giving away
compostable materials e.g. horse manure,
coffee grounds, chicken manure
• Collect leaves from the sides of roads
• Ask people for their lawn clippings
• Get shredded paper from the office if you can
• Dampen newspaper and tear into strips

14. • Ask juice bar owners if you can have the pulp
from juicers if you are there at cleanup time
• Compost mates: collect food waste from local
cafes and compost it in home or community
spaces

15. Coffee grounds

16. Shredded office paper

17. Bags of animal manure

18. Straw from the chickens’ straw yard

19. Grass clippings from neighbours

20. Leaves from the side of the road

21. Sawdust

22. Comfrey leaves

23. Why comfrey is your best friend
• Comfrey is a dynamic accumulator - it sends
down a series of deep taproots and extracts
and accumulates large quantities of potassium
(around 7%) and phosphorous (around 1%),
calcium (around 3%), magnesium and other
trace elements from the depths.

24. • These nutrients are stored in the leaves,
which can then be used to feed other plants.
• Comfrey is in effect mining nutrients out of
the soil, because of the deep taproots which
reach deeper than normal roots can go

25. Nearly finished layering

26. Compost worms

27. Compost nearly ready to use

28. Make it easy
• make do with whatever you have around
• optimal shape for a compost heap is
approximately 1m wide and 1m high and at
least 1m long
• Build the heap in thin layers of different
materials approximately 5cm thick and water
each layer before progressing to the next.

29. • When the heap finally starts to cool down
(around 2 – 4 weeks) worms will come in
• Finished compost should be dark, fine and
spongy with a pleasant earthy smell. You
should not be able to recognise any of the
original ingredients in it

30. 2 main possible problems
• It stinks: turn and add brown material –
carbon e.g. shredded newspaper
• Nothing’s happening: turn and water well.
Maybe add some manure or grass clippings,
blood and bone or comfrey.
The more effort you put in, the quicker you will
get compost

31. How to use
Like any other compost
• Compost tea
• As a mulch
• Dug into top layer of soil

32. Handmade wheelbarrow compost
sifter

33. Other types of hot composting
Biodynamic
• The heap should be built as a windrow. The
dimensions of the heap should be 2m wide at
the base and 1.5m high and as long as is
practical.

34. Jean Pain:
• compost mound of wood chips made of tree
limbs and
pulverized
underbrush.
• Produces home &
water heating as
well as methane to
use as fuel.

35. Resources
• Deep Green Permaculture
• Permaculture Research Institute article
• Biodynamic composting
• Ground to ground
• Compost mates
• Compost sifter