So what is leaf mould?
The clue is in the name. Leaf mould is the result of fungal action on dead leaves. Unlike garden compost, which is predominantly the result of decomposition, when leaves break down it is as a consequence of fungal organisms feeding on them, mouldering them down. Sooner or later the result is that we get lovely crumbly leaf mould.
This happen naturally on the woodland floor. However, in managed environments such as gardens, it is not always appropriate to let leaves remain where they fall and we do need to clear them up.
It is important to remember that in herbaceous beds, woodland gardens and more naturalised situations, decomposing leaves and vegetation shelter and nurture a large variety of wildlife and organisms. So there is a strong argument in favour of leaving them in place through the winter months.
Given that leaf mould is a natural free resource it’s a no-brainer to get going and make your own. Or in fact just collect it all together and let nature do all the work for you.
How to make leaf mould?
From the lawn:
Rather than allowing leaves to form a mat on your lawn blocking out light and air, it is common practice to rake up leaves in autumn to maintain your lawns health. An increasingly popular alternative to using a leaf rake is to set your lawn mower blades high and use it to collect the leaves. This has the added bonus of shredding the leaves which speeds up the breakdown. Or, if you are not going to make leaf mould, then going over the lawn and shredding the leaves two of three times when they are dry enough. This should chop the leaf waste into small enough pieces to help prevent them from making an impermeable mat over the grass and speed up the breakdown. Another popular option is a leaf blower. I’m not a fan of this noisy machinery or any fuel guzzling machinery for that matter. A large part of the joy I receive from gardening comes from doing things as naturally as possible, with as small an impact on our greater environment as can be managed. Yes, there are definitely times when we need mechanical help – I simply like to keep it as minimal and low impact as I can. Gentle gardening is my mindful meditation. I’d rather hear the leaf fall than the ‘leaf blower’.
From hard landscaping:
There areas such as patios, paths and driveways, where not removing leaves can be dangerous and unsightly. Besides being notoriously slippy when wet, unless you don’t mind staining on paving it is best to clear up leaves before they begin to decompose and leave their mark permanently.
From the local surrounds:
In these times of council cuts leaves often remain uncollected in windblown piles on pavements and urban greenspaces. A ready source if you don’t have your own garden leaf supply or just want to supplement it. Do however bear in mind that if you choose to collect leaves from public pavements, there may be a residue of pollutants that would best be avoided.
What to do with your collected leaves.
I use a frame of old pallets as containment. It’s cheap, flexible and easy, and the slats let air flow through the leaf stack while keeping it all together. You could use metal mesh or chicken wire. Likewise putting them in black bin liners (biodegradable ones please) will work, ensuring that the leaves are kept moist and aerated by poking a few air holes. You will find that freshly collected leaves initially take up a lot of space when they are crisp and newly fallen. For the most part the volume of leaves will decrease significantly over a few weeks once they get wet and begin to compress. In the case of leaves shredded and collected using a lawn mower the space taken up from the start is considerably less.
Fungus likes moisture and bit of air. To aid digestion so to speak. The actual break down into something usable takes time. Your leaf mould can happily be forgotten about in some quiet, out of the way place while the fungi slowly get down to business. If nature doesn’t provide enough rain then you can occasionally stir things up with a garden fork then give the pile a bit of a dousing to help things along.
By the end of year one you will have an excellent mulching material to use to keep your plants cosy over winter or suppress weeds and retain moisture in the growing months.
By year two will have a fine crumbly organic medium that is excellent for making your own composts and bulb fibre by mixing it with loam, grit sand or garden compost depending on the use you have in mind.
Using leaf mould.
Leaf mould is a fantastic mulch. I have been using it regularly over the past few years on clay soil that was heavily compacted after construction work and it has been very rewarding to see the structure of the soil improve and the plants begin to thrive. There is also the added bonus (and smug feeling) of a zero carbon footprint, zero cost and full circle process.
Next year I am going to start looking into recipes for making my own growing mediums and would be very interested to hear your suggestions. You can contact me at https://www.karenlaing.co.uk/contact/
Karen Laing is an amateur gardener and professional garden designer. She has been a member of the Caley’s board of Trustees since 2017.
Find out more on her website https://www.karenlaing.co.uk/ and Instagram feed https://www.instagram.com/karen.laing.garden.design/