Using Leafmould as a Soil Conditioner

Leaf mould is made from decaying leaves. It is an excellent soil conditioner, adding organic matter and beneficial micro-organisms. Although low in nutrients, this makes it ideal for seed germination: seedlings develop stronger root systems, giving them better resilience against pests and disease. When used in larger amounts, leaf mould improves soil structure by creating air spaces for root growth, while also acting as a mulch to retain moisture and suppress weeds.

Earthworms and fungi thrive on leaves, and their activity further improves soil 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.

• Faster to break down: Ash, Beech, Birch, Willow – ideal for making leaf mould.
• Acidic: Pine needles should be kept in a separate pile. They produce acidic leaf mould, perfect for mulching rhododendrons, azaleas, camellias and blueberries. Needles shed throughout the year, especially in spring, so they are best collected gradually.
• Thicker leaves: Sycamore, Walnut and Chestnut are slow to decay, so shred them before adding.
• Evergreens: Holly and Laurel are better shredded and added to the compost heap, where they will break down faster than in a leaf mould pile.

Note: Be mindful when collecting leaves from natural areas. Leaves left in woods, hedgerows and under shrubs provide food and shelter for hedgehogs, insects, birds and other wildlife. Whenever possible, gather leaves from your own garden, paths, or lawns rather than from wild habitats.

How to Make Leaf Mould

The breakdown of leaves is carried out by fungi. This process is slow, which is why a wait of two years is usually recommended. Leaf mould does not require worms, activators or other additives.

After two to three years the leaf mould will have a dark, crumbly texture. It improves soil by supporting soil microbes, encouraging root growth, and helping with drainage in clay soils and moisture retention in sandy soils.

Collecting leaves:

• Autumn is the best time, as deciduous trees shed.
• A lawn mower can be used to collect and shred leaves at the same time. This speeds up decomposition and, if grass clippings are included, increases nutrient content (though this makes it less suitable for seed sowing).

Storing leaves:

• Build a simple container from wire mesh or wooden pallets, in a sheltered spot to prevent leaves from blowing away. Pile the leaves as large as possible to speed decay, and moisten if dry. Leave for around two years.
• Alternatively, fill bin liners with leaves, moisten if necessary, pierce holes for air circulation, tie loosely and stack out of sight for up to two years. Keep bags in a cool, shaded spot to avoid drying out.

Tip: 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.

Using Leaf Mould

• Well-rotted (2+ years): Can be used for seed-sowing compost, or mixed equally with sharp sand, garden compost and soil for potting compost.
• Partially rotted (<2 years): Suitable for mulch, soil improvement, autumn lawn top-dressing, or as a winter cover for bare soil.