How to Make Leaf Mould: Free Mulch from Autumn Leaves

Every autumn, thousands of gardeners bag up fallen leaves and send them to landfill. Yet these same leaves can be transformed into one of the finest soil conditioners available – leaf mould – completely free.

In this guide, I’ll show you exactly how to make leaf mould from autumn leaves, explain why it’s different from compost, and share the best ways to use this valuable resource in your garden.

What Is Leaf Mould?

Leaf mould is the dark, crumbly material that results from the decomposition of autumn leaves. Unlike regular compost which is broken down by bacteria, leaf mould is created primarily by fungi over a longer period (1-2 years).

The result is a beautiful, earthy-smelling material that’s excellent for improving soil structure, retaining moisture, and providing a gentle source of nutrients.

Leaf Mould vs Compost: What’s the Difference?

While both are valuable soil amendments, understanding how compost differs from mulch materials helps clarify where leaf mould fits:

How to Make Leaf Mould: Step-by-Step

Method 1: Wire Mesh Cage (Best for Large Quantities)

This is my preferred method for making leaf mould in quantity:

1. Create a cage:
   • Use chicken wire or wire mesh fencing
   • Form a cylinder approximately 1m diameter and 1m tall
   • Secure with wire or cable ties
   • No base needed – place directly on soil
2. Fill with leaves:
   • Collect fallen autumn leaves (any type works, but see notes below)
   • Fill the cage, compacting lightly as you go
   • Water if leaves are very dry
3. Cover:
   • Use a piece of old carpet, tarp, or plastic sheeting
   • This keeps moisture in and prevents leaves blowing away
   • Weigh down edges with bricks or stones
4. Wait:
   • Leave for 12-24 months
   • Check moisture occasionally – leaves should be damp but not waterlogged
   • Add water in very dry spells

Method 2: Black Plastic Bags (Best for Small Gardens)

Perfect if you don’t have space for a large cage:

1. Collect leaves and fill strong black bin bags
2. Add water if leaves are dry (leaves should be moist, not soaking)
3. Punch holes in bags for air circulation (6-8 holes per bag)
4. Seal bags and store in an out-of-the-way spot
5. Wait 12-24 months, checking moisture once or twice

Method 3: Compost Bin (Fastest Option)

If you have a spare compost bin:

1. Fill bin with leaves only (don’t mix with other compost materials)
2. Water if dry and close lid
3. Turn occasionally if you want faster results (optional)
4. Check after 6-12 months – compost bins speed up the process

Which Leaves Make the Best Leaf Mould?

Fast-Breaking Leaves (6-12 months)

• Birch
• Hornbeam
• Beech
• Cherry
• Hazel
• Rowan

These thin leaves break down quickly and make excellent quality leaf mould.

Slow-Breaking Leaves (18-24 months)

• Oak
• Sweet chestnut
• Horse chestnut
• Sycamore
• Plane

These tougher leaves take longer but still produce excellent leaf mould. To speed things up, shred them with a lawn mower before adding to your leaf pile.

Leaves to Avoid

• Evergreen leaves (holly, laurel, conifer needles) – take many years to break down
• Walnut leaves – contain juglone which can inhibit plant growth
• Diseased leaves – some diseases can survive the leaf mould process

How to Speed Up Leaf Mould Production

• Shred leaves: Run over them with a lawn mower before adding to your pile – this can halve decomposition time
• Keep moist: Check moisture levels every few months and water if dry
• Turn the pile: Turning 2-3 times during the first year speeds decomposition
• Add activator: A handful of garden soil or finished leaf mould introduces beneficial fungi
• Mix leaf types: Combining fast and slow-breaking leaves balances decomposition

When Is Leaf Mould Ready?

Leaf mould is ready when:

• Leaves have broken down into a dark, crumbly texture
• Individual leaves are no longer recognizable
• It smells earthy and pleasant (like forest floor)
• It’s moist and friable, not slimy

Quality grades:

• 12 months: Partly broken down, good as mulch
• 18 months: Well-rotted, suitable for soil conditioning
• 24 months: Fine-textured, perfect for seed compost and potting mixes

How to Use Leaf Mould in Your Garden

1. As a Mulch (12+ months old)

Similar to bark mulch or wood chips, leaf mould makes excellent mulch:

• Spread 5-8cm thick around plants
• Leave a 5cm gap around stems and tree trunks
• Excellent for woodland plants, shrubs, and under hedges
• Suppresses weeds and retains moisture beautifully

2. Soil Conditioner (18+ months old)

• Dig into soil before planting at a ratio of 1:3 (1 part leaf mould to 3 parts soil)
• Improves both clay soils (adds drainage) and sandy soils (improves water retention)
• Perfect for preparing new beds

3. Potting Mix Component (24+ months old)

Well-aged, fine leaf mould is ideal for homemade potting mixes:

• Seed compost: 50% leaf mould + 50% sharp sand
• Potting compost: 70% leaf mould + 20% garden soil + 10% sand
• Ericaceous mix: 80% oak or beech leaf mould + 20% sand (for acid-loving plants like rhododendrons and blueberries)

4. Lawn Topdressing

• Mix leaf mould with sand (1:3 ratio)
• Spread thinly across lawn in autumn
• Improves soil structure and helps level bumpy lawns

5. For Woodland Plants

Leaf mould is perfect for plants that naturally grow in woodland conditions:

• Hostas
• Ferns
• Hellebores
• Primulas
• Cyclamen
• Trilliums

Common Leaf Mould Problems and Solutions

Problem: Leaves Aren’t Breaking Down

Solutions:

• Add moisture – dry leaves won’t decompose
• Shred leaves to speed up the process
• Mix in some garden soil to introduce fungi
• Be patient – some leaf types take 2 years

Problem: Slimy, Smelly Leaf Pile

Solutions:

• Too wet – improve drainage or punch more air holes in bags
• Turn the pile to introduce air
• Add some shredded cardboard to absorb excess moisture

Problem: Weeds Growing in Leaf Pile

Solutions:

• Improve coverage to block light – weeds like dandelions and bindweed need light to germinate
• Remove annual weeds before they seed
• Don’t worry about perennial weed roots in the mix – they’ll decompose

Collecting Leaves Efficiently

• Lawn mower method: Run over leaves with mower (with collection box) – shreds and collects in one go
• Rake onto tarp: Rake leaves onto an old sheet or tarp, then bundle up and carry
• Leaf blower/vacuum: Many models can both blow and vacuum leaves into a bag
• Ask neighbours: Many people are happy to give away bagged leaves

Final Thoughts

Making leaf mould is one of the easiest and most rewarding garden tasks. It requires minimal effort – essentially just collecting leaves and waiting – yet produces a valuable material that can cost £8-15 per bag if purchased.

Start your first batch this autumn. Even a single bin bag of leaves will give you useful leaf mould for mulching your vegetable garden or improving soil in flower beds next year.

Once you experience how leaf mould transforms clay soil or helps sandy soil retain water, you’ll never waste autumn leaves again.