What’s the learning?

There are many ways to compost. Compost piles are normally turned every week or two, a process that adds oxygen and speeds up the process of converting plant material into compost. This is called ‘hot composting’. As well as being fast, hot composting also kills many of the weed seeds in the compost pile – they get cooked!

The challenge is, you generally still get a lot of weed seeds surviving. The longer the compost is hot, the more the carbon from the plants you are composting is turned into carbon dioxide (CO2) – a gas that then floats away into the atmosphere. We want as much of that carbon to stay in the compost as possible, so we can add it to the soil in our gardens and grow more vegetables. So, this video is about how to do cold composting, a process which maximises compost output. To keep the weed seeds out, we recommend not composting weeds that are seeding – the chooks will happily eat them if you have chooks!

What you need:

• A compost bin (or not – you can just make a pile on the ground or make a bin out of old untreated wood, like that in pallets)
• A carbon source: plant prunings, hedge clippings, shredded paper, shredded cardboard, leaves, hay, straw – whatever you can source that is thick stemmed, woody (up to 1cm) or brown. A mix of sources will provide a balance of nutrients along with the carbon.
• A nitrogen source: food scraps, lawn clippings, plants such as comfrey that you can cut and they will grow back quickly. Again, a mix of sources will provide a balance of nutrients along with the nitrogen.
• Optional: seaweed, if you live near the coast, lime (supplies calcium) or dolomite (supplies calcium and magnesium), crushed egg shells (supplies calcium).

What to do:

Making a pile all once

1. Get all your materials (above) out into the garden
2. Shred your paper and cardboard
3. Make the bottom layer about 10cm thick of more woody and chunky materials. This will help air get up into the pile over time, providing needed oxygen
4. Add a layer of ‘green’, your nitrogen sources
5. Add a layer of seaweed and or other additions such as lime (2-3 handfuls) if you have them. If not, don’t worry you can skip this stage!
6. Add a layer of shredded paper/cardboard
7. Water the pile with a hose
8. Repeat steps 4-6 until you run out of materials.
9. Cover the pile with a tarp or old carpet to retain the moisture while keeping the rain out – you don’t want it to be waterlogged.
10. Check the pile after 5-6 months and when it looks like a dark soil you can use in your garden. Depending on what materials you used you may still have some woody stems present when the rest is broken down. That’s OK, just pull them out and keep them for your next pile.
11. If the compost is not ready just give it some more time. You can add water at any time if it gets too dry.

At the end of making your compost pile you should be able to take a handful of pile materials and get a few drops of water out when you squeeze it. If you can’t squeeze a few drops of water out add water until you can. If it is really wet, it will dry over time – just leave the cover off for a few days and test again. When it’s right, cover it up.

Some people like to turn the pile once, after about 2 weeks. This will turn the materials on the edges, which dry out, into the inside and help them break down. You don’t need to, the choice is yours. Any materials that are not composted at the end can be pulled off the edges and put into the next pile.

Making a pile over time

1. Make the bottom layer about 10cm thick of more woody and chunky materials. This will help air get up into the pile over time, providing needed oxygen
2. Add materials to your pile over time as you have them available. The key is to add more carbonaceous/woody/brown materials than green or food wastes. So everytime you add a bucket of food waste or some lawn clippings, you should also add in a layer of shredded paper, cardboard, or woody plant material. At the same time, add a layer of seaweed and lime (2-3 handfuls) if you have them. If not, don’t worry you can skip this stage!
3. Sprinkle water on the pile until the layers you have added are damp, but not waterlogged (see the above notes on water levels). 
4. Keep the pile covered to prevent it getting too hot from the sun or too wet from the rain.
5. When your bin is full, move to your second bin and begin filling that up. You will need enough bins that youe full one/s have 5-6 months time to sit there and become compost.
6. Check the pile after 5-6 months and when it looks like a dark soil you can use in your garden. Depending on what materials you used you may still have some woody stems present when the rest is broken down. That’s OK, just pull them out and keep them for your next pile.
7. If the compost is not ready just give it some more time. You can add water at any time if it gets too dry.