When designing a permaculture garden I try to close as many loops as possible. One of them is the flow of nutrients. The easiest way to do that is composting, there are many ways to make your own compost, and in this series, I will share my experience and some thoughts and tips. First up, is the compost bin. The most important tips for a good compost is the layering of nitrogen-rich green layers and carbon-rich brown layers (preferably 1:3), constant conditions and providing oxygen.
My current compost bin is one made out of reclaimed pallet wood with two 1m2 bays separated by an air channel, top lids and front doors. The m2 bay is advised to be able to build enough mass that it starts to generate heat which is preferred by the workers living in your compost. It is placed relatively central to the garden which makes it easy to deposit garden material and distribute compost. Ideally, your compost bay has three spaces so you always have one bay that you’re filling, one that is resting and one that you’re emptying. I chose not to do this for two reasons, 1) my garden is not that big that I can fill a 1m2 bay with compost quickly so by the time it’s full the bottom half is already halfway towards compost. 2) Even though I have a relatively large garden for a terraced house, I still have to be economic with my space, so I prioritised growing spaces over a third compost bay. To help further distribute the nutrients from my compost bin that drain away into the soil underneath I have planted comfrey on both sides. Comfrey has a long taproot and accumulates nutrients from deeper soil layers in its leaves. When the plant is mature you can harvest the leaves and use them as green mulch on other parts of the garden to release the nutrients into the soil.
The key to successful composting is to start with a good Nitrogen (N) : Carbon (C) layering balance (ideally 1N:3C but at least 1N:2C). Nitrogen is found in green matter, so fresh pruned leaves, vegetables, grass clippings etc. Carbon is the brown stuff, dead leaves, woody material, cardboard etc. Adding too much nitrogen and your pile might become too hot, soggy and smelly and burn through the present oxygen quickly. Too much brown matter and the compost will not rot very well at all. As a rule of thumb for my compost bay, I add mainly uncooked plant matter that can be grown in my local area, as this means local nature can compost them, the other bits (citrus peels, banana peels, fish bones etc.) I first add to my bokashi bin which is emptied into the compost bin when it’s done.
Next, your compost bin needs oxygen, like you, the organisms in your pile need oxygen to do their thing, so turn your pile regularly. We aim for once a week, but at least every other week. The more you turn, the quicker your scraps will decompose. As a bonus, it keeps you healthy with some good exercise :p It is for that reason that a compost bin with openings on the side like I created with the pallet slats, will work better than a completely closed one.
Lastly, you need constant conditions. The workers in your pile work best under mild conditions, not too hot, not too cold, not too wet, not too dry. So a covered bin that retains some heat, but is not exposed to full sun is perfect. That said, if you have a big garden an open pile will work just fine if you place it under the shelter of some trees for example or behind a shed.
Some tips, if it is too wet, sludgy or it starts to smell bad, add more brown matter to absorb it. If it is too dry or doesn’t seem to do anything, you can add compost accelerators. One example is a compost tea made from fermented comfrey and/or nettle leaves. Another quick way is to deposit some urine, which is high in nitrogen and pathogen-free, so safe for your compost and a great way to return some nutrients you extracted through the food from your garden if you do not have a compost toilet.
I started off with one Dalek style plastic compost bin on our balcony. I’ve been told several times that those are not optimal because they inhibit the flow of oxygen, the opening makes it difficult to turn the compost and they don’t keep the heat from the composting process very well. However, we had it in an east-facing spot near the house with just morning sun to warm it up, propped up on a pallet with a special base for a hard surface that had air holes in it, and it worked fine for us. When we moved after a year we had good compost from it. We mainly mixed cardboard and paper packaging with the contents of our bokashi in it, which probably helped as well, as that is already fermented so easy to break down. Later on, we inherited two more of these plastic bins with the house, but as I wanted to move them more central to the garden where I also had more space, I decided to build a bigger one. I am also a big believer that beautiful spaces make us happier and are more inviting to spend time in, so I try to make every new addition to my garden something that I like. I am really happy with how these turned out and by using reclaimed pallet wood and parts of an old free wardrobe they only cost me £10 for the hinges and screws.
If you have a lot of compostable waste at the same time you can opt for hot composting by layering green and brown in a bay or pile of anything over 1m2. You then turn it daily, up to weekly which allows the centre of the pile to heat up and grow fungi and bacteria to thrive. You could then create compost in a matter of weeks, compared to cold composting which takes months up to years. This is also a preferred method if you have a compost toilet as at 60 Celcius it kills off any pathogens present.
I have also seen hotbin compost bins for people who are limited in space and want to make compost quickly. They cost a bit more but are supposed to work really well allowing you to build heat without the need for a big pile.
If you have chickens you could include them in your composting process. I love the idea of the three shallow bay system in the chicken zone. I really liked the explanation in this video from edibleacres who create fresh compost weekly. You add fresh kitchen scraps to the first bay where your chickens can peck and scratch away, turning the decomposing scraps and mixing in their manure as they go. You move it to the second bay where it’s already starting to decompose and as it’s turned insects and sprouted seeds are exposed to the chickens. Then in the last bay, there are no visible scraps left and with the addition of the manure, it heats up and decomposes fully to become readily usable compost.