If you’re tired of taking bags of autumn leaves to the tip or paying the council to take them away, why not turn them into leaf mould instead?

Leaf mould is a fabulous soil improver that’s produced from decomposed autumn leaves that have been left to rot down. It has similar properties to peat – it helps to rebuild soil and store carbon – but has the benefit of being a renewable resource.

Like compost, it will improve the physical structure of your soil, increasing water retention by around 50 per cent. It also provides a habitat for earthworms and beneficial bacteria.

Making leaf mould was our family’s entry into composting. Our garden is swamped with leaves every autumn as it’s overlooked by several trees.  The cost mounted as we paid the council to take away our bags of raked leaves, so we finally decided to get two 900L Graf Thermo King composters to reap the benefits ourselves. 

What to do with autumn leaves?

The Royal Horticultural Society encourages gardeners to leave autumn leaves on borders as they encourage worm activity and increase humus content in soil. But leaves have an annoying habit of not staying where they’re put; they tend to team up with the wind to dance around and end up on the lawn or path, and in our case the hallway too.

 So it’s good to keep a balance between the leaves you sweep and the leaves you leave. Leave the leaves on soil and around trees and hedges as they replenish the soil with nutrients as they decompose, providing food throughout winter. Removing leaves can contribute to the slow death of trees from malnutrition. Leaves also protect tree roots from weather extremes.

If the leaves are dry they will blow away so dampen them with rainwater from a water butt to weigh them down a bit.

 Although leaves create a habitat for insects and pollinators, too many can attract rats and ticks so don’t let huge piles grow. Rake them off lawns and plants to prevent them smothering growth.

Stockpile for compost

Keep some leaves in storage for your compost bin; stockpile them so you have readily available Browns (carbon) to balance the Greens (nitrogen). Most people find they have a ready supply of food waste providing them with nitrogen-rich content but finding carbon-rich Browns can be harder, especially through winter.

• Store dry dead leaves in old compost bags or lidded containers next to the compost bin so they’re ready when needed. 
• You might want to wait until all the leaves have fallen unless you don’t mind a lot of raking.

How to make leaf mould

Making leaf mould is a simple, relatively slow process, relying on the action of fungi rather than the faster heat-generating bacteria of the composting process.

• To collect the leaves, you can rake them up into a pile or set your mower on a high cut setting and mow them up, using the grass collector added to the back of the mower. This mulches them up for you. You can also use a shredder.
• Shredding the leaves increases the surface area in contact with microbes, speeding up decomposition. Shredded leaves also take up less space if you don’t have much room to store them and they’re also less likely to mat down in a bin, excluding air from the compost.
• You can also whizz them up with an edge trimmer in a dustbin (like using a food stick blender) or use a pair of hedge clippers and a board.
•  Some leaves break down more quickly than others. Evergreen leaves take far longer to rot and should only be added in small quantities.

Storing leaves

The most basic way of storing leaves is to keep them in a black bin bag, pierced at the bottom and sides to allow the contents to breathe.  If the leaves are very dry, moisten them before putting them in the bag. You don’t need to add anything else – just the leaves.

If you prefer a container, the Thermo King compost bins that we use make life simpler because:

• Two large flaps make it easy to remove compost.
• The lid allows humid air to escape and is adjustable to summer and winter weather conditions to regulate air circulation.
• The base allows micro-organisms to enter whilst deterring rodents.

How can I use my leaf mould?

If leaves have been left to rot for two years or more, they can be used in seed-sowing compost or mixed equally with sharp sand, garden compost and soil for use in potting compost. The leaf mould will be dark brown in colour with an earthy smell and crumbly texture, like compost.

• As mentioned earlier, leaf mould makes great mulch and soil improver, and if less than two years old can be used as autumn top-dressing for lawns or winter-covering for bare soil. Soil needs more winter cover than you might imagine – around 5 – 7cms.

Autumn glory – leaves left around the trees at Yorkshire Sculpture Park, Wakefield.

A clean sweep

If you can’t bear to see leaves going to waste, why not join the eco-warriors all over the world who sweep pavements in their neighbourhoods to collect leaves for composting? A few words of advice if you do:

• Don’t sweep busy streets because the leaves could be contaminated with pollution from traffic fumes.
• Stick to quiet areas or alleyways where there is no traffic so no fumes and no soil/trees needing to be fed over winter. On pathways leaves are wasted, either creating a slip hazard or dispersed by wind and rain. You just need to watch out for hidden dog poo.   

Julie