Wednesday, August 10, 2011

Compost is cool

After playing around for a while with composting, we've finally got a grown up three bay hot composting system, hoorah! Last summer (and winter come to think of it) was so dry that our garden really suffered. Our gutless sandy soils just can't retain moisture or nutrients without adding heaps of organic matter and the best way to do that is with compost. It's a great way of closing the loop on our organic waste and diverting it away from landfill. As a friend pointed out it's also a good way to offset your carbon emissions since it sequesters carbon. Lastly, there are few things more satisfying than making and turning good compost...

Let me show you how I built the bays. Here's what we used:

7 pallets off the verge (best quality 'H3' preferably)
6 x 75mm wood screws
4 x 1.5m star pickets
Some sheets of tin, 3 per bay
Roofing tek screws 25mm, 5 per sheet of tin
Some wooden boards for slats (preferably wide, hard wood)
Pine timber for slats to slide into (20x20mm or 30x20mm), plus nails to attach to pallets

They're fairly easy to build, however pallets are definitely not straight when you look closely and this causes problems. Ideally you want the openings of the bays to all be the same width because this means you'll need less slats and they will all fit in any bay. Anyway, I'll get to that in a mo. Here is what they will look like:  

In a cooler, wetter climate you can probably leave the tin off to allow more ventilation, but they're good in our hot dry climate to retain moisture. First thing to do is to fit two pallets together with the back against a fence for stability. We put ours against the south facing fence to be out of the heat (compost generates its own heat and therefore doesn't need it in a warm climate) and it's a great way to use a space in the garden where you can't grow anything anyway. All pallets should be the same size and facing with planks horizontally. This allows you to bang in the star pickets and to attach screws more easily (the rear pallet in the background of the photo is oriented the other way, but I had to do this because it was slightly smaller than the other pallets). The two pallets can be screwed together with a 75mm wood screw (pre-drilled), as in the photo below. Try to ensure they are on flat ground and nicely leveled. Then fit the next side pallet in the same way. You should have a bay now and you can leave it at that or keep adding bays.

The next step is to ram a star picket in between each pallet towards the front. The trick is to adjust the pallets and star pickets so that all the bays are of equal width. Get as close as you can and then wedge small pieces of timber in between the pickets and pallets to fine tune:

Next you can attach two timber battons on each side of the pallets leaving a big enough gap for the slats. Lastly, attach the tin sheets if desired with the tek screws. We don't have a solid floor to ours, just dirt. There are pros and cons to this, you'll lose some nutrients without a slab, but worms and other beneficial beasties will be able to get into it more easily.You can also attach some wooden boards on top of the pallet ends to stop things falling down and to place your cuppa/beer on. Then cut your slats to fit with a bit of leeway. Hey presto, you have some beautiful, functional compost bays all in a row:

I think three is a good number. You have one bay composting, then you can turn it a few times and it will be ready to go. You can leave it in there and start another brew and you'll still have the spare bay for turning in to. Our bays are 1.1m square. The main cost is in the star pickets and screws. We got the tin for free from a friend and the wood for slats dirt cheap at the tip shop. I'm not sure about the legal implications of picking up pallets off the verge, but there are so many of them around I don't think they'll miss them. No-one seems to blink an eyelid when I pick them up. I like to think of them as a form of corporate sponsorship (unknown to the sponsor); thanks Cockburn Cement, you need the good PR...

Now the fun bit. We usually take a few days to gather the makings of a brew. I've been told that making hot compost is like baking a cake, you add all the ingredients at once and let it bake. We pick up as many vegie scraps as we can from the local shops (up to 0.5 cubic metres) over a few days, plus straw and manures, shredded paper, fallen leaves, etc. This seems like a lot of stuff, but most of it is free (we buy sheep poo, blood and bone and straw, but use the straw in the chook yard first).

I'm not going to give a compost lesson because really I'm no expert, but we make several layers of the following ingredients:
Vegie scraps, plus any green waste from the garden
Straw (from chooks is best)
Blood and bone and sheep poo
Shredded paper
Dry leaves
Saw dust
Worm juice
Egg cartons
Dynamic accumulators (eg comfrey, nettles)
Starter from your last brew/worm farm.

Lastly, add water (lots of it all the way through, especially if you live in hot dry Perth and you are making it in summer). You probably don't need to add worms. If you build it they will come.
Slide in the slats as you build it up and go as high as you can (we got to 1.2m last time). Then cover with something like carpet and wait for the magic to happen.

Compost is magic. You put all this waste stuff in and in go the worms, beetles, bacteria, etc and it heats up and produces beautiful, rich organic matter which will suit any plant. You can turn the compost every 3-4 days if you have the time and energy (when I first turned compost it felt great, it was like this rite of passage I was going through as a gardener).Turning will speed it up but is not essential. It should take between 3-6 weeks to make good compost.

I know what some of you are thinking: I don't have the time! Don't worry, you'll get around to it some day. It took me a while to realise that I needed to do it. Once you get the hang of it it's not that hard and you'll notice the results. Yes, you can buy compost but fresh compost is alive. How alive will it be after being put in plastic bags, on a truck for X kms, sitting in a shop for X days/weeks/months?

My dad used to make good compost. He'd pee in a bucket and pour it on. I wish he'd taught me his secret knowledge. I can't blame him though, I was probably a snotty kid who thought compost was really uncool. Now I'm older and wiser of course I know compost is very cool and an important skill. Hopefully I can pass on my knowledge to Quin, but maybe he'll be a snotty kid who thinks compost is uncool (and then realises later in life that it's not and writes about it in a blog).

We have a few other ways of composting and worm farming but these are the subjects of future posts...


  1. As Mark Twain said: “When I was a boy of fourteen, my father was so ignorant I could hardly stand to have the old man around. But when I got to be twenty-one, I was astonished by how much he'd learned in seven years.” Nice post, nice bins.

  2. This step-by-step instruction would be great for those who might not have a green thumb like yours. Hope those plants grow healthy!