Leaf mould is one of the best natural soil improvers around. It’s an enormously valuable resource for your garden. You can make leaf mould yourself – here’s how it works.
The plants and greenery in your garden can be resilient, but there are times when they could fall into decline. You can stop this from happening by giving them protective or nutritious supplements like leaf mould.
While you can buy garden compost, there’s really no reason to. Why not take advantage of the many autumn leaves in your garden? With this guide, you’ll learn everything needed to make leaf mould by yourself.
To make sure you're getting the best possible leaf mould, we've spoken to Philip Clayton.
Philip is a plantsman, gardener, author and freelance garden writer with a plant-filled garden in Peterborough.
A member of the RHS Herbaceous Plant Group, he spent 20 years at The Garden (the RHS magazine), latterly as Deputy Editor.
Prior to this, he worked as a landscaper, a role which followed practical training at RHS Garden Wisley, in Surrey. He also has a BSc Hons in Horticulture from Wye College in Kent.
His books include A Plant For Every Day Of The Year (2022), Grow: Roses (2024) and Parched (2024). He also currently works as gardener at The Manor Hemingford Grey, near Huntingdon.
Needless to say, Philip has plentiful experience as an industry expert, and is more than ready to help us create leaf mould.
What is leaf mould?
So, what exactly is leaf mould?
It’s an earthy, dark and crumbly soil conditioner, which is commonly used as a mulch or potting soil.
Formed by decaying leaves, leaf mould can provide real value for gardeners. Besides its nutritional value, it's also a useful for controlling unwanted weeds in your garden.
Of course, there's more to leaf mould than that. It's overwhelmingly nutritious organic matter, beyond what you'll receive with regular garden compost.
It does take longer to form, since most leaves will need two years to decompose (and perhaps longer), but it's worth the wait. You'll receive a light, nourishing growing media that not only promotes development, but delivers better drainage (when sifted), too.
Using leaf mould also allows you to avoid chemical solutions. This is great, since some types of weed killers could be potentially harmful to plants, wildlife, and your health.
Autumn is the perfect time to make leaf mould, as that’s when deciduous trees drop their leaves.
Philip Clayton, weighing in, says “Leaf mould is so much more valuable than regular garden compost and you are essentially making use of an abundant, and free, garden material.”
How to make leaf mould
Making leaf mould is a simple process, but to get the best results you need to follow the right steps (and keep patient!). Here’s what you need to do.
Find the right leaves
Eventually, given enough time, all leaves break down into leaf mould.
Despite this fact, there are better and worse choices. According to the Royal Horticultural Society (RHS), the best leaves for leaf mould are oak, beech, and hornbeam leaves.
These leaf types produce a high-quality product and break down more easily. Using thicker leaves – horse chestnut, walnut, and sycamore – is possible, but the decomposition process takes longer.
If you use these types of leaves, speed up the process by shredding them before adding them to your leaf pile.
Many people don't use evergreen leaves, like holly and conifer needles, but they can be valuable. They decompose slowly – pine needles could take as long as three years – but eventually make excellent leaf mould.
Adding to this, Philip explains that “Pine needle leaf mould is acidic, making it particularly suitable for mulching ericaceous plants such as rhododendrons – which require acidic soils.”
As is the case with so many things, you need to find the right materials and solutions for your situation.
Collect your leaves
This is far and away the most labour-intensive part of making leaf mould – collecting fallen leaves!
Raking is the usual approach, but you could probably speed things up with a leaf blower or rotary mower.
Using a rotary mower (after setting the blade on high) makes collection easier, and it automatically shreds the leaves too. Plus, you’ll be including some grass clippings, which should speed up the decomposition process.
Leaf mould doesn’t heat up like compost – so you won’t kill weeds or diseased leaves during the moulding process. If you’re raking, try to sort these out of the pile at this stage. Then burn or dispose of them elsewhere so they don’t affect the rest of the leaf matter.
Build a leaf bin
If you have room in your garden, building a leaf bin is a good idea. You can use netting, fencing, or chicken wire to create an open bin. This makes collecting and storing a large pile of leaves easy.
The build process is similar to a compost bin. Start by wrapping mesh wire around a frame of four wooden corner posts or supporting bamboo rods. Secure it using U-shaped staples.
It should be roughly one metre wide and high, so the leaves stay moist and dense. In general, a wider surface area is better so that rainwater can reach more of the pile.
Before you start building, choose a spot that's shielded from the wind and sun. You don't want your leaves blowing away or drying out.
Once you've collected your leaves, turning your leaf pile over with a pitchfork regularly is important. If you feel the pile is drying out, lightly water it with a hose.
…or make a leaf bag
If you don’t have room for a leaf bin, bin liners or repurposed compost bags are a good alternative.
Simply heap your leaf pile into a sturdy bin bag until it is around three-quarters full. Then shake, moisten with a hose until all leaves are wet, and then tie the bag at the top.
Improve the bag’s drainage and ventilation by piercing holes through its sides and bottom using a garden fork.
Then you can store them out of sight while the leaves decompose. Most often, people place these behind sheds or in shady corners of the garden.
Each month, give the bags a good shake to allow the air to circulate properly. At the same time, check that the leaves haven’t dried out.
Want an ideal spot to make leaf mould? Philip says “Choose a sheltered site to stop the leaves blowing away. Make sure it’s shaded from the summer sun to reduce drying out.
"The leaves will need turning every few months to speed the decomposition process and regular watering during summer and dry periods.”
How to use your leaf mould
You’ve taken the steps needed to make leaf mould, now what do you do?
Expect decomposition to take at least 12 to 18 months – though it could be two years or longer. You’ll know it’s ready when you see a rich, dark brown colour. If it’s still moist or slimy, you’re better off leaving it for another month and checking again later.
Now that you know it’s ready, it’s time to use the leaf mould.
If your leaf mould is less than two years old, it’s best used as mulch, a soil improver, as an autumn top dressing for lawns, or for suppressing weeds. You could also use it to cover bare soil through the winter months.
Use older, higher-quality leaf mould as a seed-sowing compost. Alternatively, you could mix it with sand, garden compost, and some decent soil to create potting compost. You’ll need the right mix to get the best possible soil structure.
As you can see, it’s a really versatile material.
Making the most of your garden
Producing leaf mould using your garden’s fallen leaves is a great idea. Leaves are abundant during autumn, they cost nothing, and by producing your own leaf mould, you're limiting your carbon production.
Reiterating, Philip confirms this is an eco-friendly approach.
“If you’re not buying in bagged material – unless you make your leaf mould in bin bags – you’re reducing plastic use, and by making your own organic matter you’re reducing the carbon footprint of your plot.”
You’ll be raking up leaves anyway, and leaf mould can give your trees and plants more protection and nutrition. Of course, this is just one of several autumn and winter gardening jobs that can help your garden out each year.
By following this simple guide, you’ll get an invaluable pile of leaf mould. If you need more help with this process – or any other gardening activities – read up on the latest gardening tips, tricks, and hiring advice.
If you want to bring in a professional, either contact your local gardening services or post a free enquiry – and let interested businesses get in touch with you directly.