Dead leaves are a naturally occurring organic material. For a keen gardener they can make some of the best compost that can be made. If you’ve never attempted this before, you may be wondering how to go about it.
So, here we explain how to make organic fertilizer from leaves. It’s incredibly easy. If you have a heap of dead leaves, add moisture, white-lime, turn the heap occasionally and allow time to go by. Add grass clippings if you want to take it to the next level.
The prize at the end of the effort that you put in, is a rich, naturally occurring organic fertilizer that can be used as a plant food. You can also use it for growing mushrooms. We have a post that explains this further. Take a look at ‘Can you grow your own mushrooms?’ to find out more.
The first step is to gather up the leaves before they blow away and someone else gets them. On a dry day, dead leaves are very light to move. So, you can scrape them into a heap using a rake or, as some people recommend, go over the leaf-fall area using a lawn mower that picks up and collects. This will chop the leaves as you collect. Then when you’ve harvested, one way or another, you can do this:
How to make organic fertilizer from leaves
- Start making compost with them in a bin, heap or compost tumbler.
- Store them in big bags, be aware that they must be kept dry in storage.
- Add nitrate material to balance the high level of carbon in dead leaves. This would include kitchen waste and lawn clippings.
- Mix the leaves with the nitrate material by building in alternating layers. Aim for a ratio of leaves to nitrates of about 5:1.
- Sprinkle some hydrated lime on top of the nitrate material to reduce acidity and smells.
- To speed up the process, turn over the heap or use aerator probes in a bin. This isn’t essential but it will take longer if you don’t.
- If the composting mass looks dry, add water; compost needs to be moist.
The first thing you need to know is that rotting down leaves can take a while depending on how you go about it. Whichever way you do it you will find that apart from the leaves, you will need two other ingredients – water and air.
The air comes free from all around us and for the water grey-water can be used, i.e. dish-washer water, bath water or washing machine water. It’s a waste to use clean water.
Organic fertilizer, otherwise known as compost, can be generated in two ways.
If you want speed, and most of us do, the fastest way to turn leaves into a well usable organic fertilizer involves chopping the leaves.
For the best result feed the leaves through a chopper over and over again until they are ground down to small particles. The smaller the particles are the more moisture will soak in and the faster the rotting process.
Having chopped the leaves, there are choices about how to do the rot down. You can either:
- Place the chopped material in a basic bin or container, soak with water, cover it and leave it to work. The bin or container must have adequate ventilation for the air to get in.
- Load it into a tumbler device. Ensure adequate moisture is present and rotate regularly. The tumbling action will introduce enough air into the material making for a much faster rotting process.
Can I make leaf mould in a compost bin?
Yes you can make leaf mould in a compost bin.
The simplest way is to build or buy a basic bin that will hold a decent volume of leaves. Soak the whole volume with water.
The down side to this method is that it will take about 2 years to achieve a dark, well rotted, usable organic fertilizer. We have a post that explains the time-scale involved in making compost from leaves. Find out more at ‘how long does it take to compost leaves‘.
Dead leaves must be kept moist for the rotting process to start and continue to reach the end result of dark, rich organic fertilizer.
Cover the container with a water-porous layer e.g. an old piece of off-cut carpet. This will allow some moisture into the load to maintain the required moisture level. It will prevent both over watering from heavy rain and drying out during hot dry weather.
Which ever system you use be aware that when a tumbler or container is rotting down leaves or anything else, no more fresh material can be added.
You have to treat each volume as a closed batch. If you add any fresh dried leaves the result will be an inconsistent mix of fully rotten and partly rotten material.
This means that if you have a lot of leaves to process you will need to set aside separate bins that will make organic fertilizer at different stages.
If you choose the slower simple option these containers will be in place for around two years.
How to store leaves for leaf mould
If the Autumn has provided you with a nice big heap of leaves, good for you. Look after it because dead leaves are worth their weight in gold, almost.
Make sure that they don’t blow away and end up on your neighbour’s rights because if they do you can say goodbye to that.
Bag them up and store them somewhere dry and ready for when you want to make organic fertilizer.
What is leaf mould
Having collected and bagged all the valuable leaves that you can, you can now decide what you want to do with them. To make leaf mould the best and easiest way is to make a few drainage holes in the plastic bag and saturate the leaves within with water. The surplus water will drain out leaving moist leaves which will become mouldy and start to rot.
Leave the bag outside for the rain to get at it. This will provide enough moisture for the process to continue. It’s important that the leaves don’t dry out. You also need to place the bag in a sheltered spot or the wind may blow it around.
Storing leaf mould in this way for about 1 year you should be able to use the contents of the bag. You will notice that the structure of the leaf material will have largely broken down but you will still recognise it as leaves.
You will notice that the contents of the bag will turn white with the fungus that grows on the leaves. It’s this that releases the nutrients from the leaves that become usable to growing plants.
To become fully rotten compost you will need to leave the bag for at least one more year.
Leaf mould uses
If you have bags of leaf mould that are about a year old you can use them to dig into a garden patch in the autumn. This will introduce the nutrients that leaf mould can provide into the ground.
Be aware that by doing this the leaves will carry on rotting in the ground or on the surface. If you have a good worm population in the ground these will digest the leaves as they break down.
The continued rotting this way will result in some nitrogen being taken out of the ground which you may not want. It may make more sense to leave it in the bags for another year to fully rot down. By doing this it will take nitrogen from the air and not the ground.
Another use for leaf mould is to spread a thick layer around shrubs and small sapling tress. This will provide valuable nutrients to these larger plants which won’t be so nitrate sensitive and it will smother any weeds that try to come through.
Leaf mould accelerator
Leaves are organic in the true sense of the word i.e. ‘carbon based and once living’. For any carbon rich material to rot down there has to be nitrate rich material. The process doesn’t require a massive amount of nitrogen but it does need some.
Depending on what your preferences are, a nitrate supply can come from a number of sources. Make the leaves wet then add the ammonium nitrate powder. This way it will stick to the leaves and work it’s way in.
Another method of introducing nitrates into the mix may be considered to be rather Anglo Saxon but it is highly effective. This involves using your own urine. It’s a very rich source of nitrates and there is a guaranteed plentiful supply.
Leaf mould cage
What is a leaf mould cage? This is a very simple construction for those who want to be a bit more industrial about gathering leaves and turning them into something useful. It’s much better to load leaves into a large container rather than fiddling around with lots of plastic bags.
All you need is a place in the garden where it’s out of the way but easy to get at. You will need some chicken wire and a minimum of four wooden stakes. You will need a hand full of nails to nail the chicken wire to the stakes and a large hammer or something heavy enough to knock in the stakes.
This is what you are aiming to construct.
When complete you will have plenty of capacity for lots of leaves. Depending on how much leaf material is available, year after year, you could build more than one cage. This way you can leave a cage undisturbed for two to three years and allow the contents to rot down completely.
Leaf mould allergy
You need to be aware of this. We are looking at mould when we make leaf mould. It’s a very beneficial medium to have in the garden providing soil nutrients and it’s certainly something that shouldn’t be wasted. But the mould in leaf mould is a fungus that produces microscopic spores.
When we handle or disturb leaf mould, as we do just by using it, the spores become airborne and it’s difficult to avoid breathing them in. Some people with any type of breathing condition are likely to be effected by this.
A similar problem use to occur in years gone by on farms when making hay. In a wet and difficult hay-making season some hay would be stored with a higher moisture content than would be desired.
This would cause the hay to turn mouldy. When this was taken out to be fed to livestock the spores from the mould would, unavoidably, be released into the air and those handling it would breath it in.
Some where effected quite badly with, what came to be known as, ‘farmer’s lung’, a condition for which there appears to be no cure.
So when you handle leaf mould that’s been forming for several months, expect to see mould dust. Do what needs doing on a breezy day and do what you can to avoid breathing it in.
What leaves make the best compost
It doesn’t matter what type of leaves are available to you when the autumn/fall season comes. They can all be easily swept up into a heap.
When they are chopped and put through a composting process, fast or slow, they all have the ability to produce a usable organic fertilizer.
Pine needles can be considered as a separate entity. It may be better to process these in batches on their own as pine needle mulch and pine needle compost tends to be acidic. This is ideal if you have ericaceous plants. These are plants that prefer acid soil e.g. rhododendrons and heathers.
How to compost leaves quickly
There are more things you can do to accelerate the process of turning dead dry leaves into organic fertilizer. This involves adding other components which complement leaves to make for a good balance.
The problem with trying to make good compost from just leaves is that there aren’t enough nitrogenous compounds for an effective balance. Making compost from just leaves can take 2 years or possibly longer, see more at Rolypig.com/how-long-does-it-take-to-compost-leaves
There are compost activators available that will move things along. These are a potent nitrogen source which can be used if all you have are leaves. It will compensate for any absence of green material e.g. kitchen waste or lawn clippings.
Composting leaves in plastic bags
Here’s something you can do if you have a useful surplus of leaves in a productive year and run out of bins, boxes and tumbler space.
Get some plastic waste bin sacks, preferably strong plastic, and load them to being almost full but you can tie off the neck. Saturate the leaves with recycled water, tie off the neck and make a few holes in the base of each bag for free drainage.
Place the bags on bare earth to allow worms to get in. Depending on the local conditions you may be lucky and find the best worms for compost making turn up naturally. Micro–organisms living in the ground beneath the bag will find their way in and help with the whole process.
A refinement to this would be to mix the leaves with green nitrogenous material like lawn clippings or add a compost activator.
You could also add a small quantity of ready made compost as a starter because this will contain a helpful amount of micro-organisms to get things going.
Does bagged compost go off?
If the concern here is that it may smell then this will be due to kitchen waste that has become acidic. At this stage the material has become preserved rather like pickling.
You may also see a lot of flies. A really effective way to stop this and produce a quality compost is to add lots of dead leaves. It will make a big difference if they are chopped and thoroughly mixed with the green waste.
Aim for a mix of about 25 parts chopped leaves to 1 part green waste. This way you will be swamping the green waste, which contains a high level of nitrates, with enough carbon-based material to get the job done.
Do this and there will be no smell, no flies and a near perfect balance will be achieved. A good quality compost is guaranteed if you can get the ratio of Carbon to Nitrogen right (25 Carbon : 1 Nitrogen).
Worms for compost
You will know if your compost is forming well if you see worms in it.
Sometimes they turn up from the ground around and find their way in. If the conditions in your compost are suitable they will take up residence in a big way and start to breed.
It’s quite possible that the first you will know of worms in your compost bin will be masses of them appearing when you open the lid. The most suitable breed of worm is the ‘Tiger worm’, named so due to the distinctive striped-hoops, they breed very quickly and they know what they like.
The only down side of using a compost tumbler is that worms can’t find their way in from the ground very easily. The only way to overcome this is to find some worms and physically put them in. The exception to this is the Rolypig (see more at Rolypig.com) this is because the Rolypig sits on the ground and the worms easily find their way in.
If you do intervene and add worms make sure that the compost in the tumbler is well rotten. Worms aren’t happy in material that isn’t rotten, they can’t eat or digest fresh food.
“Dead leaves are free,
so make the most of them”