Every autumn, gardens send away the best soil conditioner they produce. How to make leaf mould, and why it beats almost anything you can buy.
Leaf mould is the quietest miracle in gardening. It requires no turning, no heat, no activator and no money — just leaves, time, and the patience to let nature do what nature does. And it produces a soil conditioner that is better than most of what garden centres sell in plastic bags.
What it is
Leaf mould is the product of fungal breakdown of fallen leaves. Unlike compost, which is bacterial and hot, leaf mould is a slow, cool process. The result is a dark, crumbly, earthy material that improves soil structure, holds moisture, and makes an excellent mulch and seed-sowing mix component.
How to make it
Collect leaves in autumn — preferably from deciduous trees, and ideally a mix. Oak, beech and hornbeam break down slowly and make the best mould; sycamore and horse chestnut break down fast and can be mixed in. Avoid evergreen leaves and diseased material. Stuff them into a wire cage or a couple of large bin bags with holes punched in them, keep them damp, and leave them alone.
How long?
One year gives you a coarse mulch. Two years gives you crumbly, dark leaf mould ready for potting mixes and seed compost. Oak and beech can take three. The wait is the only hard part, and it is not very hard — the pile does not need you.
How to use it
Use coarse leaf mould as a mulch around trees, shrubs and perennials. Use the finer, two-year material as a soil conditioner, dug into borders, or mixed half-and-half with garden compost for a superb potting mix. It is especially good for ferns, hostas and woodland plants, which evolved with exactly this material.
The economics of patience
A large garden produces hundreds of kilos of leaves every autumn. Bagged leaf mould costs money; the raw material costs nothing and is currently blowing down your street. The only investment is a wire cage and the willingness to wait. Very few things in a garden offer that exchange rate.
Start this autumn. In two years, you will have the best soil improver in the garden, and you will have made it out of what everyone else raked away.