Hot composting is when you layer together carbon and nitrogen materials (food scraps, grass clippings, manure, straw, leaves, wood chips etc) into a large pile all in one go. Add water as you go and hey presto, your compost should be steaming hot within a few days. Cover it to keep moisture in, tum it when it starts to cool and within six to nine months you should have glorious compost
Out of sight is out of mind, so the best place is somewhere close to the hub of the garden. A hot compost heap can be free standing, or you can build a structure out of wooden pallets, tin, untreated timber or straw bales. A plastic compost bin can work if you keep the moisture levels up by watering frequently.
You need enough materials to make a pile at least one metre high, one metre wide and one metre deep. Stockpile the materials until you have enough. You’ll need a balance of carbon-rich and nitrogen-rich materials:
•Carbon (browns) – straw, leaves, shredded newspaper, cardboard, prunings, wood chips, dried grass clippings
•Nitrogen (greens) – food scraps, fresh grass clippings, weeds, manures, comfrey, yarrow, seaweed
It’s just like making a lasagna. Alternate layers of greens with browns, sprinkling water between each layer. A 10 cm layer of straw could be followed by a 10 cm layer of food scraps, followed by a 10 cm layer of shredded newspaper, followed by 10cm layer of grass clippings and so on. Don’t forget the water, every layer should be damp like a wrung-out dish cloth.
Cover Once built to the magic one-metre-cube dimensions, cover the heap with some old carpet or black plastic.
The more you turn it, the quicker you’ll make compost. How often comes down to your time and enthusiasm. Turn it at least once after the heap begins to cool down, anywhere from two to eight weeks. This really mixes the cake and encourages the heap to reheat. Your compost is ready when you can’t recognise any of the original ingredients (usually six to nine months). You should have a brownish-black, rich, crumbly, soil-like substance to use on your garden.
Check moisture levels to see if your heap is too dry. Add water, especially around the edges. Make sure the heap is covered to keep moisture in.
My heap stinks
A smelly ammonia-like odour means you have too much nitrogen (green). Re-turn the heap adding more carbon (eg straw) as you go.
Everything seems right but it’s not heating up
Make up a nitrogen-rich slurry (eg a quarter bucket of manure mixed with water) and pour it over the heap a few times over a few days to fire it up. Pee is also a fantastic compost activator.
Aaargh! I’ve got rats and mice
Rats can be attracted by your heap, no matter what you put in it or leave out. A cat or traps are the way forward here.
Bugs and flies – yuk
These critters are part of the decomposing process. To deal with an attack of tiny vinegar flies, fork over the top 30-50 cm layer, add some lime and cover well.
Kitchen scraps and garden waste make up a third of household waste. Putting them in the landfill can be harmful as organic waste releases methane, a climate change gas. The Dr Compost project helps people in the Queenstown Lakes district to reduce their waste and feed their soil by composting at home.
For composting advice, come along to a Dr Compost workshop, join the Dr Compost Facebook & Instagram communities or email firstname.lastname@example.org
We love your composting questions and stories!
Dr Compost is funded by Queenstown Lakes District Council and delivered by Wastebusters.
You add a bucket of food scraps
All animal manures are nitrogen (greens) and are great added to the compost heap with a balancing layer of browns. Chicken manure has the most nitrogen, followed by pig, cow, alpaca and horse. Try to avoid manure from recently drenched animals.
As a heap matures, compost worms are a fantastic part of speeding things up. Once added to a three-bay system, they will multiply and move between heaps.
Theoretically you can put all your weeds, seeds included, into a well-managed hot compost heap. I tend on the ‘just in case’ side with weeds that have seed heads or flowers, or which are just downright nasty (like couch). Chuck them in a bucket of water instead, let them rot down and you have a weed tea. Dilute four to one and feed your plants.