A rake progress!
Don’t leave your leaves to moulder where they fall, says Monty Don. Gather them all up and you can turn them into gardening gold
AS I WRITE this, a brisk westerly wind is sending the leaves billowing and scattering across my garden like berserk confetti. But if you think of fallen leaves merely as autumnal litter that adds another gardening chore to your already over-burdened life, you are terribly mistaken. Fallen leaves are just entering another phase of their contribution to any garden and the only sensible, practical thing to do is to make leafmould.
Leaves fall when cells break down at a point called the abscission layer between leaf stalk and twig. A corky scar forms over the wound that this causes, protecting the tree from infection.
Some trees cannot form this scar tissue so they do not drop their dead leaves until the new ones start coming through the following year, which is why beech and hornbeam keep many of their russet leaves all winter until the new ones literally push them off in spring.
Poplar, birch and willow fall early but an oak that is protected from the worst of the wind can hang on to its leaves into the new year.
Evergreens do not change colour, and keep their leaves for more than a year. In practice ‘evergreen’ means that the leaves can overwinter before being renewed in spring. However, although they do eventually fall to the ground, do not add evergreens to your leafmould pile as they take much longer to break down.
If you do not touch fallen leaves they will eventually turn into leafmould, in the same way that all dead or rotting vegetation will make compost. Walk through a beechwood and the ground will be made up of a deep layer of the stuff. But the chances are that it will not be where you want it and in the process will both look unsightly and possibly do damage by becoming damp and rotting other plants such as herbaceous perennials. The answer is to gather up the leaves and keep them in either a container or bin bags.
Leaves decompose mostly by fungal action rather than bacterial digestion (compost, in contrast, is made mostly by bacteria). This means that leaves do not heat up much as they decompose and need to be damp.
Dry leaves can take a very long time to turn into the lovely, friable, sweet-smelling soft material that true leafmould invariably becomes.
This means that you should gather leaves when they are wet or be prepared to dampen them with a good soaking before covering them up with the next layer. It also helps a lot to chop them up.
The easiest way to do this is to mow them, which also gathers them up as you do it. Of course, if the leaves are too wet they will clog the mower up, so I try to sweep and rake them into a line when dry, run the mower over them and then give them a soak with the hose when they are in a special chicken wire-sided bay.
If you don’t have room for a dedicated leaf bay then put the mown leaves into a black bin bag, punch a few drainage holes in the bottom, soak them and let it drain, and then store out of sight. This system works perfectly well.
Either way the leaves will quietly turn into leafmould over the next six months without any further attention.
You can also use them in spring in a halfdecomposed state, as a good mulch around emerging plants.
Why go to this trouble? Because leafmould is gardening gold. It is a perfect soil conditioner and mulch for all woodland plants as well as improving any potting compost and a very good substitute for peat.
It is dead easy to make and costs absolutely nothing. So go on, treat yourself, make the most of your precious fallen leaves.