A cat hiding in a pile of leaves.

Leafmould is made from decaying leaves.  It is an excellent soil conditioner, adding organic matter and micro-organisms to the garden.  Leaf mould is quite low in nutrients, which makes it suitable for seed germination as the seedlings develop a strong root system, which will help them remain healthy when threatened with pests and diseases.  If you have enough, leaf mould makes an excellent soil improver. The coarse organic particles help create air spaces, vital to let roots penetrate the soil. Leaf mould also makes a good mulch that aids moisture-retention and helps prevent the growth of weeds.

Earthworms love leaves, as do fungi, and their action in the soil will improve its fertility.

What Leaves Can Be Used?

All leaves will eventually break down into leaf mould, however the qualities of different leaves will affect the finished product and some are better used in the compost as they will break down faster there.

Leaves that break down faster such as; Ash, Beech, Birch and Willow are perfect for making leaf mould.

Pine needles are worth gathering and placing in a separate pile as they produce acidic leaf mould, which is ideal for mulching ericaceous plants, such as rhododendrons, azaleas, camellias and blueberries. Pine needles will shed throughout the year, but especially in spring, so need to be gathered gradually for a pine needle leaf mould pile.

For thick leaves like sycamore, walnut and chestnut, it is best to shred them before adding to the leaf mould pile, as they are much slower to break down.

Evergreens such as holly and laurel, are also better shredded and added to the compost heap, where they will break down faster than if added to the leaf mould pile.

How to Make Leaf Mould

There is no magic involved -  it is the action of fungi that break down the leaves. These fungi are quite slow workers, so that is why a two year wait is recommended. Leaf mould does not need worms, activators or anything else to break down.

After two to three years the leaf mould will have a rich, crumbly consistency. It’s great for enhancing soil, feeding the soil microbes that encourage healthy root growth, improving drainage in heavier soils and moisture retention in lighter soils.

Deciduous trees drop their leaves in autumn, so this is a good time to gather leaves for starting a leaf mould pile.

You can also collect leaves from the lawn using a lawn mower, as this not only shreds the leaves and hastens rotting but also adds grass clippings, so increasing the nutrient value of the leaf mould. 

You can mix some grass clippings to your heap of leaves. This will speed up the process, but remember that the resulting mould will be richer and so won’t be very suitable for seed germination.

To store the leaf mould, make a frame from wire mesh or wooden pallets.  Ideally this should be in a sheltered part of the garden to ensure that the leaves are not blown away. Make your leaf heap as large as possible to speed up decay, and moisten it periodically if it becomes dry. Leave for two years for the fungi to do their work.

Alternatively, if you have less space, you can place the leaves into a bin liner, moisten if they are dry.  Pierce holes in the bag to allow for air circulation then tie the top loosely and stack the bags out of sight for up to two years.

Keep in a shaded, cool spot in the garden, where the leaf mould won’t be dried out by the sun.

Using Leaf Mould

Good quality, well-rotted leaf mould (more than two years old) can be used as seed-sowing compost. It can also be mixed equally with sharp sand, garden compost and good quality soil for use as potting compost.

Half rotted or ‘young’ leaf mould that is less than two years old can be used as mulch, soil improver, autumn top-dressing for lawns, or winter covering for bare soil.

NOTE - If your leaf mould pile is slow to break down, try turning it occasionally to aerate the leaves and speed up the breakdown process. Make sure that the leaves do not dry out, moistening the pile if necessary in dry weather.