Homemade compost is the very best fertility for your vegie garden because its alive, minerally rich and stable. Your plants reflect this by growing steadily + strongly, and the reduction in pests and disease is quite something. Homemade looks and smells nothing like bought – it really is far superior.
And though it sounds like a mission to make your own, its not at all hard, nor is it time consuming. By time you’ve gone to the shop and bought a bag – you’ve made a heap! And because I cold compost, there’s no turning either, just a weekly water if need be.
My easy peasy process, starts with an efficient setup – read about that here. Go one step further and reduce the amount of compost you need, with a few simple design strategies and garden habits.
Before we make our pile, let’s get to grips with the 5 key ingredients that make an awesome compost.
Composting maths
Stable, mineral rich compost is the end result of micro organisms transforming raw, organic matter. The organisms are the key – they do all the work. Our job is to entice them in with the perfect feed and habitat.
Here’s the sum of what they want:
- Air – from a twiggy base, stalky stuff in the mix to create air pockets, air holes in the bin and by poking hole in the finished pile.
- A variety of food – brown (carbon), green (nitrogen), coarse stuff (air + carbon) and fine stuff (heat + nitrogen)
- A good balance of carbon + nitrogen
- A variety of mineral rich ingredients
- Moisture – from fresh green matter, watering and covering the pile
Pretty simple equation, aye. Lets look at each in a bit more detail – the details hold the key.
Air
Airflow is key – we want healthy aerobic compost, not putrid, anaerobic goop.
Achieve this in 3 ways – with a bin that’s well aerated (ie not solid plastic!), a base that creates air flow and by making holes throughout the heap at the end.
A base of thin twigs lays an airy foundation. By thin, I mean with a diameter of about 1cm or less. A mix of fresh and dry is ideal, but either or is fine.
I like using twigs because as well as airflow, they innoculate compost with beneficial fungi that digest lignin – those tough fibres in the dry/ carbonaceous ingredients. These fungi are essential for an even overall breakdown, and are an aspect that is most missing from home composts.
A variety of food
Variety is the important thing here – different sizes and textures and ingredients bring a variety of biology – the more the better!
Be certain that all the ingredients you use are spray free. Fungicide, herbicide and pesticide residues kill all the biology we are trying to foster.
A good balance of carbon and nitrogen
Getting the balance of carbon and nitrogen is key – and its not as tricky as it sounds! This balance is referred to as the carbon:nitrogen ratio. Written as C:N.
The organisms that do the bulk of the work in your compost, thrive on organic matter with a C:N ratio of 25-30:1. This happens to be the C:N ratio of garden waste and weeds! Huzzah!
Use a mix of stems and stalks and dry bits and foliage and juicy green stuff – just like you get after clearing up old crops and weeds. Make this the bulk of your composts, and all will be well.
Here’s a list of C:N rations for common ingredients – just to give you a feel for it. It’s a good general guide, but of course, the variables are many.
Chook manure 7:1 Best used decomposed, and sparingly – no more than 10% of your total heap
Cow manure 20:1. Best used decomposed, and sparingly – no more than 10% of your total heap
Seaweed and coffee grounds are around 20:1. Best used fresh
Grass clippings 9 – 25:1 Best used fresh. If the lawn is diverse with stalky dandelions and plantain, and cut when long, the carbon is greater about 25:1, but if it’s mono ie one type of soft grass and cut low you’re looking at about 9:1
Weeds, crop residue and soft, small prunings are about 25-30:1. Best used fresh.
Pea straw 29:1. Best used decomposed. Beware non organic pea straw – its full of fungicide.
Leaves and straw are about 50:1. Best used decomposed.
Sawdust is an eye watering 325:1. Best used thoroughly decomposed, if at all. Run this through your chook house and yard to balance it with nitrogen from their manure, or your paths so its well rotted. I’d never add sawdust to a compost, not even broken down stuff.
Keep the balance in an -ish, homemade kind of way by using a large variety of garden waste, and balance out high carbon, by mixing with high nitrogen and vice versa.
Mineral rich ingredients
Sources of minerals are everywhere in nature – herbs, leaves, weeds, seaweed, fish waste, food scraps, manure or shells.
Use a wide variety of mineral rich ingredients and you’ll promote the right kind of biology our soils need to stay balanced.
Lime is so tricky, I prefer to steer clear of it unless I know its needed via a soil test. Too much, is, it seems, worse than too little. I prefer to focus on building soil biology – they’ll rectify most everything. Garner calcium from fish waste and seaweed through your composts.
Moisture
Water each layer as you make it, until its barely moist. Or do as I like to do – and make compost on a drizzly day.
Cover it when its done, to retain moisture and ensure an even breakdown. Use either a thick layer of carbonaceous ingredients, or sacks, or carpet – whatever you have.
Check in on it once a week to feel temperature and moisture levels, and water it as needs be.
Lets make compost!
I make my compost progressively. Ideally a heap is made all in one go, but in reality, it takes me a few goes at it. Try to finish your heap within a few weeks of starting it.
Make your compost on the ground – whether in a bin or a free standing heap. Soil contact is key so the biology can move in and out at the different temperature stages.
Gather ingredients by going for a garden wander with the barrow and chop up weeds, old foliage, spent crops, plants that block the paths, adding them as you go. The smaller you chop the better. At a minimum go for about 20cm bits.
Tip your load beside your compost bin and mix it together.
Lay your twiggy base – 5 cm high is a good measure to hang your hat on. If you don’t have twigs go for woody prunings of herbs, dry ponga fronds, bracken or something similar – spread it all out to the edges of the bin.
From here, start to layer up your pre mixed garden waste in about 10 – 15cm deep layers. To each layer of garden waste, add:
- a few handfuls of mineral rich ingredients
- a few good handfuls of decomposed carbonaceous ingredient from your OM stash. Use more than this if there wasn’t much stalky/ dry stuff in the original mix, or less if there was a lot. Feel your way – compost is a flexible thing!
- As an added bonus, you can at this stage add some biology with a few handfuls of compost or good soil, some dilute raw milk, molasses, or a biological brew poured on.
Toss it together and spread it right out to the edges – be pedantic! You want the top of the heap to be flat, not a hump. Moisten it.
Keep layering in this way until you reach the top of the bin, or atleast 1.2m high.
Poke a few holes in the sides and top with a stake or crow bar, then cover it over.
Apart from maintenance watering, there’s nothing to do but wait. This is cold composting (as opposed to hot), and its my personal fav because though it takes alot longer (about a year) it retains the beneficial fungi which then spread out into your garden with the compost.
Finished compost
At the end of the year, or close enough to it – your pile will have shrunk to next to nothing. Don’t feel ripped off – its concentrated and potent – you only need a little!
It’ll smell lovely, be a dark colour and a mostly peaty texture interspersed with some rough bits. Those chunky bits are awesome and likely/ hopefully! covered in fungal threads. Don’t expect it to look like the bought stuff – it wont, but by goodness, it’ll grow you some beaut vegies!
Make a new heap once a month spring through autumn, and you’ll soon be running your garden on your own brilliant brew.
Troubleshooting
If your compost is ammonia smelling and sludgy, its gone anaerobic – there wasn’t enough air because you used too much fresh greens + fine stuff and/ or it got too wet. Break it apart. Add lots of carbon and minerals and biology, mix it altogether then re stack it.
If your compost ends up musty, crusty and dry – you’ve let it dry out and/or used too much carbon. Use it as mulch and start again!
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Hi Kath,
What is the best way to use chicken droppings for compost?
I use an upright plastic compost bin and I currently just chuck them in there daily with all the garden clippings and vege scraps etc
Cheers
Tracie
Hows your compost coming out Tracie? If it’s all good keep doing what you’re doing. Tweak it only if its not working I say 🙂
I do get excited reading your posts on making soil. Great read. By some act of serendipity I have been unintentionally doing something along these lines already when trying to decide what to do with garden waste. I just need to tweak a few things now to make it home faster.
Hurrah for soil excitement! I love it when intuition takes you there.
happy composting
Kath
Hi Kath. Thank you! This is such a great way to make compost easy . I’m new to your posts (and learning heaps, thank you)) so aren’t up with some of your terms. Please tell me what is EM and what is a Fadge?
Hey Susanne – learn all about the wonderful EM (effective microorganisms) at emnz.co.nz. Stimulate the natural processes in your soil by pouring on the microorganisms. A fadge is a woolpack – its the headline picture in the compost article. Hope this helps! Kath
Hi Kath, inspired by your excellent info on composting (thanks heaps haha), I’m building a pile this afternoon – can you tell me if putting the green stuff through the mulcher is as effective as chopping it into 20cm pieces? Or does that make it too fine a mix for adequate air throughout? Thanks
Mulch away! Smaller bits = faster compost. Good luck!
Hi Kate,
Thank you very much for the compost update and I like the new way your do compost. I don’t garden as often and my compost is made of everything and some food scraps. I will start doing it your way as it is easier and I can do piles of compost around my section, fabulous, I thought that was possible but I will now.. Can you tell me where I can by fadge and manure, is bunning an ideal place to buy them. Also can I use horse manure as well for my compost thanks.
Roxanne
Glad you love it! Secondhand fadges are available on trade me and at Farmlands – not sure about Bunnings. And yes any manure is good. My recommendation is to rot it first. Stick it in a covered pile on the edge of your vegie patch… benefit from the run off. Use the rotted stuff.
Wishing you awesome compost!
Kath
Hi Kath
Thanks for your great piece on composting. I too have been making compost for a few years and recently have read a book which lead me to reassess what I was doing particularly about carbon : nitrogen ratios. However on reading your piece I think I have got a bit hung up on that. Thanks for putting me straight.
The list of herbs which you give under the section ‘Activators’ is really excellent and I certainly can do a lot more with herbs that I grow. I always have thought that worms did the work – microbes weren’t part of my compost picture!!
I have a couple of questions:
1. Iodine? Is it necessary to buy stock iodine to water into the heap?
2. How would you use pony poo in your heaps?
Thanks for your website – great to have a source of information where the conditions are similar to the Manawatu.
Graeme
Palmerston North
Hi Graeme – great to hear your thoughts. I don’t use stock iodine and the thought has never crossed my mind! so for me the answer would be no to that. Horsey poo is so full of weed seeds my preference is to rot it first – an old fashioned dung heap is my go to. Pile it up, put a cover on it, have the pile somewhere you will benefit from the run off (mine is tucked into the herbs around the edge of my vegie patch). Use it rotten – fabulous stuff!
best
Kath
Hi,could you tell me where to get more soil tested please? Moving to a a newish house in inner city Christchurch.
Hey Jude, thats a good cal to get tested – hop onto my goods and gurus page https://www.ediblebackyard.co.nz/resources/links/ – all the links are there. all the best Kath
So would you not compost your food scraps in amongst all your garden waste? I compost food scraps, and carboard, and garden waste together in one big bin (and also have various piles around the place of other garden waste). What about including cardboard in the compost bin (toilet rolls etc.)? I’ve heard it’s good to help give more carbon.
I dont include food, but that’s no reason for you not to – there is no right or wrong way here. And of course – add all the things – old clothes, boxes whatever its all organic matter. Though you dont need more carbon per se if you are using general garden waste but once again – do the thing that works for you.
So with your manure you leave it out of the compost pile and have it in a separate pile on its own? I’ve got two piles on the go with quite a bit of maure already through it, along with seaweed, grass clippings, leaves, cardboard, some straw and coffee grinds.
I sure do. The acid test is – are you making awesome compost. If so – then keep right on doing what you are doing. If not scroll through my notes and find something to change and try again. Enjoy!
Hi Kath. Thanks for this great post. I’m new to composting so have a few questions… Thank you in advance… I have heard that you shouldn’t put fresh sawdust in your compost, is that correct? I have a Bokashi bucket and reading the info on the box you have to seriously dilute the liquid that you drain off i.e 2tsp to 5 litres; this means I end up tipping most of my Bokashi juice out because I can’t keep up with it which seems super wasteful. Any tips? Thanks heaps!
Fresh sawdust is for paths and chicken houses, rotten sawdust for everything else. Pile it up and let it rot or better yet mulch your paths with it! As for bokachi juice I’m a little confused by your question. I dont worry about ratios, just top the bottom bucket with juice in it up with water and use it on compost heaps, gardens, chookyard, septic tank, pour it down the drains to keep them healthy… so many uses! Hope this helps!
Awesome, thank you 🙂
Thanks heaps Kath, for all your advice. I’ve built a 3-walled pallet compost bin and been regularly adding garden weeds, mainly grass, for a few months (haven’t turned or covered it). Was pretty full when I went overseas and after two months it has significantly shrunk down though the top looks still like grass not compost. From when I first added material it’s been about 9 months (Sep to May) and I wondered if it’s ready to use, at least the bottom half or so? Even if ready now, is perhaps spring the better time to bring it out onto the vegie patch, meaning just let it sit till then or does it loose/leak its goodness?
On a general practical level, wondered if you recommend to either fill pile then retire it till ready (and start a 2nd one) OR once in a while (every 6months??) move top to the side to retrieve compost from underneath?
Hi Annika
Your intuition is right in thinking that by spreading it now and leaving it itll be a bit of a waste – spread it and right away sow a greencrop or plant a crop is the best way.
Use the stuff thats broken down and smells good on the garden as and when you need it – best before planting.
Use the stuff that isnt broken down as mulch, or recycle into another pile.
Get as broad a mix of ingredients as you can for best results.
Keep it as simple as you can with compost – try to not think too hard about it, and trust what feels good.
Youll get the feel for it the more you do it. Your plants tell you all you need to know by how well they grow:)
Enjoy! Kath
Hi there, this article is so interesting, it’s made me rethink my black bin composts. I’ve always worried about open bins attracting rats. Is this concern negated if there are no food scraps in an open compost heap or are rats likely to make a home in it anyway?
Hey Linda, Thanks for bringing up rats! Yes they’re about no matter what we do, though less attracted by far without food in the equation. Although any dry, warm sheltered place is a potential house….. ! Trapping and a relaxed mindset are the key. Try an open pile out and see how it goes for you.
Hey Kath, love your generous sharing of information, thank you.
I’m going to start compost piles – been waiting for 3 bins to be built and 18mths later, still waiting!
Do I need to clear the area of Kikuyu grass first, or can I build on top of the grass?
Oh yes please do clear the grass first. Chuck some black plastic down – perfect timing in hot summer weather.
I’m guessing there is nowhere on your property that is kikuyu free? If there is, use that instead.
If not, you need to come up with a cunning plan to mitigate the kikuyu coming into your bins in the future because it will be back! And quickly! Ideas are position the bin on the edge of the chicken run, or some other stock, or leave a ‘weed break’ so you can mow or weedeat right up to the back wall of the bin…..
Hi Kath
Why do you say pea straw is best decomposed before putting in compost heap? “Pea straw 29:1. Best used decomposed. ”
I have just bought a big cylindrical roll of organic pea straw… it was baled August 2023 … IS that “decomposed”?
IF not in compost – I will use as mulch and laying down as a start of a new garden ?
Decomposed Mary, means no longer in its pristine original state, in the process of breaking down. Something you would notice with your eyes not with a date. Use it either way – in compost or to begin a garden is awesome. K x
Hi, I have discovered your wonderful website today and just loving all the pages and advice. Thank you!
Is there a way to use chicken compost fresh?. Is there a way to age it/compost it without using a compost heap?
Many thanks
Mimi
Hey Mimi all organic matter decomposes. Chook manure is best decomposed – all your answers here https://www.ediblebackyard.co.nz/om-is-your-guardian-angel/ K x