Homemade compost is the very best fertility for your vegie garden. 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!
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.
Lets start by getting a few key concepts under our belts.
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 spaces between the stalky stuff and the bin. A heap with good airflow doesn’t need turning.
- A variety of food – brown (carbon), green (nitrogen), coarse stuff (air + carbon) and fine stuff (heat + nitrogen)
- Mineral rich ingredients
- Moisture
Pretty simple equation, aye. Lets look at each in a bit more detail – the details hold the key.
Air
Airflow is key – we need our heaps to be aerobic, not putrid and anaerobic.
Achieve this in 3 ways – with a bin that’s well aerated (ie not solid plastic!), a base that lets 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 they also innoculate your heap with beneficial fungi that digest lignin – the tough fibres in all your 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.
And then there’s the carbon nitrogen ratio of the organic matter you use. This is written as carbon:nitrogen or C:N. The organisms that do the bulk of the work in your compost, feast 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! Make this the bulk of your composts, and all will be well.
Use this list to give you a feel for C:N. The ratios can only ever be estimates – variabilities are huge!
Chook manure 7:1 Best pre rotted
Cow manure 20:1. Best pre rotted
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/or cut when long, the carbon is greater about 25:1, but if it’s all one 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 pre rotted. Beware non organic pea straw – its full of fungicide.
Leaves and straw are about 50:1. Best used pre rotted.
Sawdust is an eye watering 325:1. Best used thoroughly pre rotted. Run this through your chook system to balance it with nitrogen from their manure, or your paths so its well rotted.
As you make your compost, balance your ingredients in an -ish, homemade kind of way by mixing the high carbon stuff with high nitrogen stuff and by mostly using garden waste.
Mineral rich ingredients
Source your minerals from either homegrown mineral rich herbs, weeds, seaweed, crushed shells or rock dust. Steer clear of artificial mineral amendments and never add individual minerals to your soil, even with a soil test! Add them to your compost.
Without a soil test, stick to natural sources, and count on a wide variety of mineral rich ingredients to promote the right kind of biology our soils need to stay balanced.
Moisture
Water each layer as you create it, or do as I do – and make compost on a drizzly day! Your goal is to keep the heap barely moist.
Cover it when its done with either a thick layer of carbonaceous ingredients, or sacks, or carpet – whatever you have, to retain moisture.
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.
Each layer of compost needs to be spread right out to the edges. Be pedantic! and avoid creating a hump, you want a smooth ish top for even heat distribution.
Lay your twig base. Spread it out to the edges.
For each wheelbarrow load of chopped up garden waste, add a generous few handfuls of mineral rich ingredient, and a few good handfuls of extra, pre rotted carbonaceous ingredient. Stir it altogether. Moisten it then layer it on top of the twigs, spreading it out to the edge.
As an added bonus, you can at this stage add some biology. Easily done with a few handfuls of compost or good soil, some dilute raw milk, or a biological brew poured on.
Keep layering it in this way until you reach the top of the bin, or atleast 1.2m high.
At this stage poke a few holes in the sides and top with a stake or crow bar, then cover it over.
Apart from maintenance watering, leave your heap to cold compost. It takes a year but is well worth it because cold compost, unlike hot, retains beneficial fungi. when you spread your compost, you innoculate your garden with these allies – they are the heart and soul of your gardens wellness.
At the end of the year, or close enough to it will have shrunk to next to nothing. Dont feel ripped off – its concentrated and potent – you only need a little! It’ll smell lovely and be dark, a mostly peaty texture with rough bits through it. No worries about those chunky bits, they’re awesome, likely 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 enough be running on your own brilliant brew.
Troubleshooting
If your compost is ammonia smelling and sludgy, its gone anaerobic – there’s not enough air in there! You’ve used too much fresh green fine stuff and/ or its gotten too wet. Break it up. 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.