Leaf Mould is composted leaves. Once the leaves have fully rotted down, the leaf mould is a rich brown/black material your own organic seed or potting compost! If you can produce large enough quantities, then leaf mould can be used as a very good mulch.
OK, so what’s the complicated bit?
Actually, none of it is really complicated. Every autumn, every forest floor is supplied with a new layer of leaves that rot down and eventually become part of the soil of the forest floor. Essentially, this is leaf mould. The only difference when you ‘make’ leaf mould is that you pile it into heaps so that you can harvest it when it has rotted down.
What is it that turns the leaves into leaf mould?
Principally, it is the action of fungi that break down the leaves. These fungi are quite slow workers, so that is why the two year wait is recommended. Leaf mould does not need worms, activators or anything else.
Sounds great how do I make it?
Well, all you have to do is gather wet leaves into a pile, somewhere where they won’t blow around. Easy, isn’t it?
The simplest option is to gather the leaves and put them into plastic bags or into a home-made wire mesh container.
Where is the best place to make the leaf mould?
Find a shaded, cool spot in the garden, where the leaf mould won’t be dried out by the sun. For instance, if you are using the plastic bags, then you can place these under a hedge, oil tank or behind the shed. If you are making the wire cage, then just be sure it is in a shady, cool area.
Do I need to add anything?
Well, the leaves should be damp, so if they are dry when you gather them, give them a good watering. Or you could take the easy option, and simply gather the leaves after a shower of rain! You also have to make sure that air can access the leaf pile this is why making containers out of wire mesh is a good idea. If you have gathered the leaves into plastic bags, be sure to punch a few holes in the bottom of the bags. The moisture and oxygen are vital for the microbes that work to break down the leaves.
What can I use it for?
Leaf mould is quite low in nutrients, which makes it excellent 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.
What types of leaves can I use?
You can use any type of leaf, but leaves from different trees have different qualities that may affect your leaf mould. For instance, leaves from conifers and other evergreens are more acidic than those from deciduous trees. As a result, evergreen-based leaf mould is great for acid-loving plants such as rhododendron and azalea. However, if you want to use the leaf mould for neutral or base loving plants, then it is best to use only deciduous leaves.
How long does it take?
Again the type of leaves used will affect the rate of decomposition. Generally, it will take up to a year or two to make leaf mould. Beech leaves are one of the quickest to rot, while tougher leaves such as oak, sycamore and horse chestnut will take a little longer. Most gardeners use a mix of whatever is falling in their garden. Conifer and evergreen leaves will take 2 3 years, while pine needles will take longer.
Is there any way I can speed it up?
Yes. If you shred the leaves (by running over them with a lawnmower) before you add them to your heap, then the leaves will take less time to decompose. This may be especially desirable if you are using pine needles to make an acidic mould. You can also 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.
What happens if I use it before it has fully rotted?
It may not be suitable for seedlings if it is very coarse, but there is no harm in using it as a mulch. The partly rotted leaves will continue to break down after you have spread the mould in your garden. Earthworms love leaves, as do fungi, and their action in the soil will improve its fertility.
Will it smell?
No. In fact, if there is any smell from your leaf pile it will be one of woodlands a lovely aroma!
How often should I make leaf mould?
Well, because leaf mould takes longer than one year to develop, you will need to make some every year so that you can have an annual supply. Then, by the time the first piles are ready, you should only have to wait another year before the next batch and so on.
What’s the secret ingredient?
Patience and a bit of memory loss! Once you have made your leaf piles, whether in wire mesh containers or plastic bags, the best thing you can do is forget all about them! Let nature take its course and in a year or two you will be surprised by wonderful piles of compost in your garden!
I tried making leaf mould a couple of years ago, but I still only have a pile of leaves why isn’t it working?
Most likely, the leaves aren’t wet enough. Remember you are depending on living organisms (fungi) to break down the leaves for you, so you must supply them with sufficient oxygen and water. Let the rain get at the leaves to make them sodden, or water with water from your water butt.
Text, Photographs and Images © Irish Peatland Conservation Council, Bog of Allen Nature Centre, Lullymore, Rathangan, Co. Kildare. Email: firstname.lastname@example.org; Tel: +353-45-860133.