Hot composting

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Somewhere in time space continuum we as humans have misplaced some of our composting knowledge! It hasn’t gone far, just a wee blip in the system. Somewhere in here we have started to think a compost heap is somewhere at the furthest out of the way place in the back of the garden onto which we chuck anything and everything from the garden and the kitchen.  Most of the time nothing happens, we’ve grown a few extra rodents and created a pile of dry organic matter.

Do not fear there is hope and with a few tweaks you could be producing lush crumbly  compost.

What is hot composting?

Hot composting is when you bring together different organic materials (food scraps, grass clippings, manure, straw, weeds etc) mix them up into a large pile all in one go, add some water and hey presto you’ve made a compost heap.

Sounds easy, and it is, you just have to follow a few steps.

Step 1. Decide where to put your heap

The best place is somewhere close to the hub of the garden, not in a distant to-be-forgotten corner of the garden. Composting is cool, be proud of your composting, show it off. You can really funk up a compost heap to make it look aesthetically pleasing. This heap can be free standing, or you can build a structure out of wooden pallets/tin/timber/straw bales/plastic units.

Step 2. Collect Ingredients

It’s just like making a cake. You need enough materials to make a pile one metre high, one metre wide and one metre deep. The ingredients are divided into two categories:

  1. Carbon or browns – rich materials such as straw/hay, dried grass clippings, shredded newspaper/cardboard
  2. Nitrogen or greens – rich materials such as food scraps, grass clippings, weeds, animal manures

Step 3. Build the heap

It’s just like mixing a cake – alternate layers of greens with browns sprinkling water between each layer. So a 10cm layer of straw followed by a 10cm layer of food scraps followed by a 10cm layer of shredded newspaper followed by 10cm layer of grass clippings and so on. Remember the one metre rule –  one metre high, one metre wide and one metre deep.

Don’t forget the water, every layer should be damp like a wrung-out dish cloth!

Step 4. Cover the heap

Once built to the magic one metre dimensions, cover the heap with some old carpet/black plastic/straw and leave it to cook. It will cook, check it after a few days to see if it’s hot.  Check the trouble shooting section below if nothing seems to be happening.

Step 5. Turn the heap

This comes down to you, your time and enthusiasm. It is possible to turn your cake into compost in under 20 days but this is labour intensive. If you were to leave the pile giving it a sprinkle of water when its dry, you would produce compost in six to 12 months. Turning it at least once after a couple of weeks is advisable. This really mixes the cake even more, it encourages the heap to heat up again, giving you the opportunity to assess how the compost heap is performing. The more you turn it the quicker you will make compost.

Step 6. Glorious Compost

You can tell its ready when you can’t recognize any of the original inputs. You should have a brown/black rich soil-like substance. Use it in your garden.

Trouble Shooting

My compost heap didn’t heat up?

Check the moisture leavels. Is it too dry? Add more water. Is it too wet? Take the cover off, get a stick, put a hole in the middle to let some moisture escape.

My heap stinks

Could be your nitrogen/carbon (green/brown) ratios are out. If there is a smelly ammonia like odour you have to much nitrogen/green in the heap. Re-turn the heap adding more carbon/brown as you go.

Everything seems right but still not heating up?

Too much carbon/browns may be the problem. Make up a nitrogen rich slurry. A quarter bucket of manure mixed with water poured over the heap. Do this a few times over a month or as needed.

Aaargh!  I’ve got rats/mice and labradors

Rats and mice. Though it is possible to build vermin proof heaps it’s not very practical for most people. A cat or a few traps is way forward here. Bury any food scraps in the middle of the pile, and don’t include meat, bones, fish, oil or fat which may attract them.

As for the labs – good luck.  No really,  you need to cover the heap up so that it can’t get at that delicious smelling buffet. Options here are an old piece of carpet/piece of black plastic/big piece of cardboard. Weigh it down at the edges to stop your overly friendly (and food-loving) labrador. It may be easier if you have a structure to contain your compost heap, rather than a free standing one.

Worms, bugs and flies –  yuk

After a compost heap has done its heating up, it cools down and other critters join the decomposing process. Sometimes you will get a mass hatch of fruit fly-like bugs which like acid. Sprinkle the top of the whole heap with some lime and cover well (see above answer for covering).

Is horse manure green/nitrogen or brown/carbon?

All manures are green/nitrogen. They vary in intensity/nitrogen content. The most potent you have is chicken manure followed by pig/cow/alpaca/horse.

Can I put my weeds into the heap?

Yes and no. Theoretically you can put all your weeds in, seeds included. But the reality is some weeds such as Fat hen can have as many as 5000 seeds per plant. If you successfully make a hot compost and turn it a few times at the right times, you should destroy them all. I tend on the ‘just in case’ side. Better to avoid putting weed seed heads into the heap, just in case we miss a few or a few hundred.

Couch should also be fine, but I tend on the side of extreme caution with this super weed. Leave it in the sun to solarize, and then leave it some more. This weed is the cockroach of the plant kingdom.

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