If you have a lot of leaves (>10 litres, a bucket load), you need to tweak the recipe to ensure they HOT compost.
If you only add thick layers of leaves into the HOTBIN, it is unlikely they will rise above 20-30C as the woody nature means they are hard for bacteria to digest and hence heat is released slowly.
To HOT compost autumn leaves, see the recipe below:
How to HOT Compost Autumn Leaves
There are two parts to successful composting of autumn leaves.
1) Adding a nitrogen source to balance the high carbon in leaves
2) Ensuring that there is enough ‘easy to digest’ waste (e.g. greens, food waste, shredded office paper’ (which creates heat quickly) to keep things hot whilst the hard to digest woody material (in which heat is released slowly) are also digested. In some cases solving (1) & usually solves (2).
Here’s what you need to do to ensure you get the best out of your HOTBIN
Step 1: Shred leaves
Leaves tend to form a dense matted layer that restricts air and oxygen flow within the HOTBIN. We advise shredding the leaves (e.g. using mower or a hedge trimmer).
Step 2: Mix leaves with easier to digest materials like food waste
Many people simply will not have enough food waste to mix with high volume autumn leaf fall. You can cheat a little by adding another easy to digest waste to go with the leaves such as chicken poo, chicken pellets, or a sprinkling of blood bone meal.
The ideal waste to mix with autumn leaves is grass lawn mowing – unfortunately, it is rare in UK to be able to get the mower out in Autumn as it is too wet and compacts the lawn soil. If you have room storing leaves in a wire frame box ready for spring and first grass cut can work really well . (Avoid sealing in black bags – the leaves will go anaerobic (see below for anaerobic method).
Step 3 – Do not add too many each time – little and often is best
More than 10cm (20 litres) of cold wet leaves in one go will “stall” the HOTBIN. The cold leaves will lower the temperature of the HOTBIN below 20°C and the heat production falls below that needed to re-heat. So store the leaves in a pop up bag, protected from rain and add over a couple of weeks – you’ll be amazed how fast they compost.
If you have a large garden with lots of trees and mounds of leaves then possibly doing a little bit each week in the HOTBIN is impractical. Try the following – shred the leaves (e.g. using lawn mower), store in a wire frame or cold compost heap until spring. Mix with first grass cuttings in large volume piles. Turn occasionally.
Leaf Mould Versus Composting
If you are collecting leaves into a wire frame then you might go down the route of just leaving them in the box and waiting 1-2 years for leaf mould.
Leaf mould versus ‘bagging’ i.e. anaerobic digestion
Many compost sites note that ‘bagging’ leaves in black plastic and tying off will create a black slime that can be used as compost. What this really means is you are anaerobically digesting the leaves down to compost. To an extent this is ok, our point would be AD creates methane and you are releasing a GHG that is 24 times more harmful than CO2. And we hope you would agree that every little bit avoided helps.
Aerobic composing is carbon neutral. Also to be honest – the black bags absolutely stink when you open then!