At my last gardening course lesson, I finally found out what they mean by "brown" and "green" compost. You're supposed to keep a balance of in your compost heap, and I'd been doing it all wrong because I'd been taking the brown and green instruction too literally.
In fact, in this context, the word "brown" is used to refer to matter that's rich in carbon and "green" is used to refer to things that are rich in nitrogen. A lot of the things that are rich in nitrogen (like grass clippings) are genuinely green and a lot of things that are rich in carbon (like wood) are genuinely brown. The problem is that not everything in the brown (carbon) category is actually brown and not everything in the green (nitrogen) category is genuinely green (for instance, tea leaves, coffee grounds and potato peelings all fall under the "green" category).
People sometimes use other terms instead of brown and green, but I don't actually find those any more helpful. The greens are sometimes instead referred to as "soft" or "hot" and the browns are sometimes referred to as "hard" or "cold", but actually, that wouldn't help me work it out either. What I find most helpful in distinguishing the two lists is that the nitrogen-rich greens are quick to rot and the carbon-rich browns are slow to rot. I've got enough experience of compost heaps to have a sense of what's going to rot quickly and what's going to stick around for ages that I can quickly work out which is which. But having a list is really helpful, so here it is:
| Greens
(= nitrogen-rich ingredients = soft ingredients = hot ingredients) (quick to rot) |
| Grass clippings |
| Raw vegetable peelings |
| Tea bags, tea leave, coffee grounds |
| Young green weed growth (avoid weeds with seeds) |
| Soft green prunings |
| Animal manure from herbivores (e.g. cows, horses, rabbits, guinea pigs) - don't use manure from non-herbivores at all |
| Comfrey leaves |
| Nettles |
| Urine (diluted with water 20:1) |
| Browns (= carbon-rich ingredients = hard ingredients = cold ingredients) (slow to rot) |
| Cardboard (e.g. cereal packets, egg boxes, toilet roll tubes etc.) |
| Paper (including junk mail and shredded paper) |
| Bedding from herbivore pets (e.g. rabbits, guinea pigs) - hay, straw, shredded paper, wood shavings |
| Tough hedge clippings |
| Woody prunings |
| Old bedding plants |
| Bracken |
| Sawdust |
| Wood shavings |
| Fallen leaves (but a better use of them is to make leaf mould) |
Now you need to what to do with these ingredients. This depends on whether you want a cool heap or a hot heap or to go a hybrid route. I'll either be going the cool route or the hybrid route, as the cool route's the easiest and my back thanks me for doing everything the easiest way possible. Here are the three options:
 |
| Upcycled compost bin at the Carshalton Community Allotment made from discarded fridge doors to help keep the heat in (the perspex lid on the top is usually kept shut) |
1. Gather enough material to fill your compost container at one go. Some of this may have been stored in a cool heap and have started to rot slightly. Make sure you have a mixture of greens and browns.
2. Chop up any tough items using shears, secateurs, a sharp spade (laying items out on the grass to avoid jarring) or a shredder.
3. Mix the ingredients together as much as possible before adding to the container. In particular, mix items that tend to settle and exclude air, such as grass clippings and shredded paper, with more open items that tend to dry out. Fill the container, watering as you go.
4. Within a few days the heap is likely to get hot to the touch. When it begins to cool down or a week or two later, turn the heap. Remove everything from the container or lift the container off and mix it all up so that the outside of the heap is on the inside and vice versa. Add water if it is dry or dry material (browns) if it is soggy. Replace the bin.
5. The heap may well heat up again. The new supply of air you've mixed in allows aerobic microbes to continue their work. Step 4 can be repeated several times, but the heating will be less and less each time. When it no longer heats up, leave it undisturbed to continue composting.
NB If you have a bad back you can compost in smaller containers. The smallest container our teacher knew of anyone composting in was the one in the picture below and he said she got results in just six weeks by tossing the compost regularly.
Cool heap
1. Collect enough compost materials to make a layer at least 30 cm high in the compost bin. Add green materials then mix in some straw, woody prunings and/or scrunched up cardboard to help create air spaces in the heap. It might help if you start the heap with a few woody plant stems or small twigs at the bottom, as this will help improve circulation and drainage.
2. Continue to fill the container when you have compostable material. Make sure you put both greens and browns in.
3. When the container is full (which it may never be, as the contents will sink as they compost) or when you decide you've added enough just leave it to finish composting (which could take up to a year) or go to step 4.
4. Remove the top layers of the heap. If the lower layers have composted use these on the garden. Mix everything else together thoroughly. Add water if it's dry or dry material (browns) if it's soggy. Replace in the bin and leave to mature.
Hybrid heap
1. Fill your heap as you create waste (like for the cool method).
2. Turn it when you have time (this will help it heat up).
You can turn it as much or as little as you want, but the more you turn it the quicker the compost will be ready.
How to balance brown and green materials whichever method you're using:
1. Add both greens and browns.
2. If the heap gets soggy and smelly add more browns.
3. If the heap gets dry, add more greens.
When is your compost ready?
When it turns dark brown and smells earthy. This can take as little as six weeks if you're using the hot heap method and put a lot of effort in, but is pretty likely to take over a year.
No comments:
Post a Comment