Everything you need to know about hot versus cold composting | Gardening 101 | Gardening Australia

Josh provides the lowdown on hot versus cold composting methods. Subscribe 🔔 ab.co/GA-subscribe
Composting is part of Josh’s life routine; he loves it so much he has both hot and cold composts on the go with multiple versions of each. He helps explain which method’s right for you.
Cold compost:
Cold compost is largely made up of kitchen scraps - the most regular type of organic matter most households produce.
Josh uses large open bottom bins, partially buried to keep out rodents and other pests. When it comes to position, Josh places his bins under his deciduous pear tree. It shades his compost from the heat in summer and when it loses its leaves in winter it allows the sun to warm the bins, keeping the microbes working.
While cold compost is relatively low maintenance and easy to manage, you must be patient, as it may take up to six months until it’s ready to use.
Josh’s recipe for cold compost:
Kitchen scraps are usually full of moisture and rich in nitrogen so it’s a good idea to balance that with a layer of fine brown organic material that is high in carbon.
Add a layer of any of one of these: wood shavings, dry leaves, even old toilet roles or paper that can also be used to line your scraps bucket. Microbes will breakdown the dry material as part of the decomposition process, but the added organic material also provides structure to the pile which is important for aeration. Air is important so the compost doesn’t become anaerobic, or sour, producing ‘stinky’ gases like methane and hydrogen sulphide.
The aim is to keep your compost ‘nice and sweet’ but if it does become sour and smelly you can lightly sprinkle some ordinary garden lime.
Next, give your compost a good forking, to open it up to get some air in so it remains aerobic. Josh does this every few weeks to help break things down.
He also has two compost bins on the go as one gets filled up the compost from the second is ready to go and can be emptied.
But something that cold compost can’t do is kill off weed seeds and plant diseases like powdery mildew, to do that you need to make hot compost.
Hot compost:
Hot compost is largely made up of garden clippings - they’re too valuable a resource to throw away. The decomposition of pruning and spent plant material are a source of carbon and nutrients to benefit your garden. Instead of throwing them away, you can reintroduce them to your garden as compost.
While Josh has used bins for his cold compost, he’s constructed bays consisting of a frame made of salvaged steel, some steel sheeting and timber including timber panels at the front for his hot compost - this helps keep things nice and contained and tidy.
Josh’s recipe for hot compost:
Gather all your clippings in one large batch of at least one cubic metre to get it nice and hot to give things a nice ‘cooking’. Then it’s just a matter of putting the right ingredients together gradually building up layers. Your layers of fresh leafy chopped up garden material are high in nitrogen and dry pruning’s are high in carbon.
- Add a 50 to 100mm layer of dried plant material like chopped up dried broad bean stems
- Sprinkle of pelletised poultry manure
- Spray some water
- Add some more green leafy pruning’s
- Add some soiled straw (Josh got his from his rabbit hatch)
- Add more pelletised manure
- Spray more water
The main thing to remember is to roughly use two-thirds fresh green material to one-third dry material and add manure for extra nitrogen and water to kick things off.
Josh uses two bays, allowing the first batch to ‘cook’ while the second bay is used to store more mature compost. Once the latter is empty he can transfer the first bay into the second empty bay and in doing that give it a second ‘cooking’ adding some extra moisture and manure and chopped fine greens to get the mix ‘just right’. This ‘second chance’ will get it hot again and hopefully kill off any weed seeds and plant pathogens.
Hot or cold compost - choose one which is right for you or like Josh, do both.
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[@prubroughton2327]

hot compost also makes a lovely hot box to germinate seeds early too

[@GardeningAustralia]

Thanks for the tip Pru!

[@prubroughton2327]

my kitchen scraps go to hens except tea leaves, banana skins and crushed egg shells which go to my 2 wheels bin worm farms everything else to 3 hot compost bins 1 to use one maturing and 1 underway add waste from home kill as well, well buried, no flies, or smell if placed in middle and really heats up bed

[@augustinekopa6560]

Yes I love doing both composting techniques thank you so much for sharing

[@GardeningAustralia]

Thanks for watching!

[@ren8240]

If I clean out the chickens pooey straw nesting boxes once a week & throw it in the compost, will it affect the mix/balance negatively? 🐔

[@thomasa5619]

Probably just assume it’s a “green” and throw in some browns like shredded paper or a bit more straw or whatever

[@ObscurumDux]

No, it helps add nutrition and nitrogen, aslong as you balance it out with with carbon ingredients such as cardbord, newspaper or dead leaves!

[@machspeed2200]

1:26; Methane is an odourless gas

[@ObscurumDux]

But methane is commonly made from a source of decay so from stank, you get odourless gas if separated correctly

[@TasHikingAdventures]

young guns gardening Tasmania shoutout to my boss 😂

[@kathyc3312]

Does the second cooking destroy the worms that come in after it’s first cooking?

[@thomasa5619]

They’ll just leave and come back again

[@fCLEF007]

Never works for me.

[@MaxIQ77]

Looks like a full time job

[@westaussieeggs8867]

well, gardening is just that, however, it is good for the soul (mental well being, NOT A CHORE), IF YOU REGARD IT AS A FULL TIME JOB IT IS NOT FOR YOU.