By Sarah Wilson
Discovering how to make leaf mould might not be at the top of your list when it comes to enjoyable ways to spend time in the garden, but in its own way it can be a rewarding pastime – honestly! That thick layer of autumn leaves covering your lawn, flowerbeds and paths needs to be swept up anyway as it will smother grass, encourage mould on plants, and is a haven for slugs and snails. So when you clear up the leaves why not store them in a bin or bin bag where they will break down into a wonderful humus-rich soil conditioner called leaf mould that you can use all around the garden.
Read on to find out how to do it. You'll thank us when your soil starts looking lush. And if you want to have a go at making your own compost too, head over to our guide on how to compost for expert tips on getting started.
What is leaf mould?
Essentially, leaves are collected and stockpiled en masse, allowing them to compost down naturally over the next year or so. During that time, nothing else is added to the mix and it doesn’t need tinkering with like traditional compost. So you can just forget about it. By the time it's ready, you’ll have lots of rich, crumbly stuff to use in the garden. The material isn’t rich in nutrients like some types of compost, but it is still beneficial. It makes an excellent mulch for beds and borders, and it can be dug into the ground to improve its condition. It contains high levels of humus, which will help the soil to retain moisture and enable it to hold onto nutrients.
How to make leaf mould
Leaves from deciduous shrubs and trees are broken down into leaf mould by fungi. This is different from normal garden compost, which depends on the action of bacteria. Small quantities of leaves can be added to the ordinary compost bin (you can find the best compost bin for your budget in our buying guide), but the vast piles we get in autumn would upset the compost balance. For this reason, they’re best treated separately.
The best leaves to use for leaf mould are small types from oak, beech, lime and hazel trees, all of which break down easily. Thicker leaves like sycamore and horse chestnut take longer. There’s an argument that if you mix different types it’s a problem because they rot down at different speeds, but then again are you really going to sit there and sort out the different leaves?
Collect leaves from your own garden and if you don't have enough offer to do friends’ or neighbours' gardens as well. You can rake them up, but if you have a rotary lawn mower with a grass box it’s easier to rake them all onto the lawn and run over them with the mower. This shreds the leaves as it collects them, which speeds up decomposition – and is particularly useful for bigger, tougher leaves. Check out our top picks for the best lawn mower in our buying guide.
Can you make leaf mould in a compost bin?
The collected leaves need air and moisture to break down. They're not as heavy as traditional compost materials so they don’t need strong, elaborate bins. Stuff damp leaves into an old plastic sack, punch lots of holes in it, tie the top and tuck it somewhere out of the way outdoors for a year and you’ll get leaf mould. You can also buy jute sacks for making leaf mould. You don’t have to punch holes in these, but otherwise use them in the same way.
What about making a leaf mould bin?
Make a traditional leaf mould bin out of chicken wire or steel mesh supported by wooden stakes. Or check out builder's skips for wooden pallets. You will need four to fix together in a square. Alternatively, you can buy a square wire mesh compost bin (try Wayfair). Site the bin on the soil, somewhere out of the way. Load in your leaves and spread them evenly, but don’t pack them down hard. Leave the top open to the elements. If they get dry, water them, but otherwise that’s all you need to do. Additives like Garotta, which speed up garden compost decomposition, won’t help leaf mould to break down.
In a year or so the pile will have shrunk down considerably. Beneath an outer casing of brown leaves you’ll find wonderfully crumbly black or brown compost-like material. This leaf mould makes a great base for home-made potting compost and it’s a great soil improver too.
Is leaf mould good for vegetables?
Leaf mould material isn’t rich in nutrients like some types of compost, but it is still beneficial. It makes an excellent mulch for beds and borders, and it can be dug into the ground to improve the soil condition. It contains high levels of humus, which will help the soil to retain moisture and enable it to hold onto nutrients. But plants and vegetables will still need some kind of fertiliser to boost growth as well. Want to learn about mulch and its benefits? Our guide to mulching is a great place to start.
Should you turn leaf mould?
It's not necessary to turn the leaf mould as you would compost. Don't open the bag or disturb the bin until the following autumn. By this time the leaves will have turned into a coarse crumbly material that will be perfect for using as a mulch around plants. If you want a finer compost that can be dug into the ground as a soil conditioner wait another 12 months before decanting the contents.
Dos and don'ts of making leaf mould
✓ Collect large volumes of leaves to make leaf mould. The process works best with big amounts, and the leaves shrink a lot when they decompose.
✓ Keep the leaves moist. If the weather is dry for long periods, water your leaves – preferably with rainwater from a water butt.
✓ Break down tougher deciduous leaves by mowing over them with the best lawn mower or using a leaf blower/sucker with shredding facility.
✗ Burn autumn leaves – it’s a waste of a good resource and environmentally damaging. If you can’t make leaf mould, collect the leaves and take them to the tip for green-waste recycling.
✗ Mix large amounts of evergreen leaves or conifer needles in with deciduous leaves, as this will slow the decomposition process.
✗ Assume you’re feeding plants by adding leaf mould to the soil. Leaf mould is an improver of soil structure, so plants will still need some kind of fertiliser to boost growth.
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