How to Make Leafmold - Gardener's Gold

, written by Benedict Vanheems gb flag

Leaves in a bin bag ready for making leafmold

There’s something akin to alchemy in the making of leafmold – the idea that out of nature’s discards comes the most deliciously crumbly gardener’s gold. For those of you unfamiliar with leafmold it’s simply wondrous stuff. Earthy, dark brown and smelling like a woodland floor in spring, it’s what you get when leaves rot down over time. Leafmold can be use as a mulch, soil conditioner, potting mix or seed compost. It’s a benign fellow, low enough in nutrients so as not to scold tender seedlings but with just the right qualities to dramatically improve soil structure and boost its water retention.

If there’s one thing that isn’t in short supply in autumn, it’s fallen leaves! So it’s rakes, scoops and wheelbarrows at the ready as we prepare to collect some of this plenty and transform it into something special.

Leafmold Takes Time

Unlike a compost heap which generates heat and relies on bacteria to break down its contents, leafmold piles are a far more sedate affair. Fallen leaves are generally broken down by fungi, which slowly wend their way through a leaf’s structure, softening then digesting it for dinner. All this takes place in cool conditions, so that while compost takes a few months to reach maturity, leafmould usually takes a year – even two – before it’s ready to be put to good use about the garden.

Raking leaves
Raking leaves

This begs the question, why bother? Why not simply add the leaves to the compost bin? Certainly small quantities of leaves may be added to the composter but with so many leaves coming at once this arrangement is soon likely to become unstuck. Leafmold’s unique properties make it worth the very minimal effort that’s required to make it; all you are in essence doing is piling up the leaves into one place (in such a way that they don’t immediately blow away) then forgetting about them until the end result is ready to use. And that’s it.

Collecting Leaves for Leaf Mold

As well as collecting the leaves from your garden you could try sourcing leaves from public places. Avoid leaves from busy roadsides which are likely to be full of pollutants, some of them nasty and slow to dissipate – you don’t want these ending up on your vegetables beds!

While leaf blowers make short work of the job, unless you work for the local parks department or have a particularly large garden they may not be the most economical or practical solution. I’d always opt for my trusty spring tine rake. Half an hour spent raking does the job just as well and provides a free workout to boot. Always rake in the direction of any wind to avoid repeatedly going back over the same ground. If you’re collecting leaves from a lawn then consider using a rotary mower, which will shred the leaves and speed up the process while introducing a few grass clippings for additional nutrient content.

Not all leaves are equal. The holy trinity of fallen leaves are oak, beech and hornbeam. If you have one of these in the garden you’re in luck, as these three trees produce the best-quality leafmold. Other deciduous tree leaves also work well, though thicker leaves such as chestnut (horse and sweet), walnut and sycamore will take longer to break down. Tough, evergreen leaves like holly or laurel take too long for even the most patient gardener and are best shredded before adding to the compost heap. Pine tree needles can be collected to make an acidic leafmold suitable for ericaceous plants such as the blueberry.

Making the Leafmold

There are two options for making leafmold: the easy option and the even easier option. The easy option involves constructing a wire frame using chicken wire supported in the corners by sturdy posts. Bigger volumes of leaves work best, offering a buffer against weather conditions, so ensure your frame is at least a meter (3ft) wide and deep. Fix the chicken wire to the posts with galvanized fencing staples and position the whole setup in a sheltered corner of the garden. Periodically check your leafy investment, adding water if the leaves seem dry. A tarpaulin cover will help to keep the contents more consistently moist.

Leafmold bin

There are all sorts of leafmold accelerators on the market. Save your money and use what comes naturally – your pee. Urine can be applied directly by gentlemen members of the household (make sure the neighbours can’t see you!) or, more discretely, collected indoors before pouring over the pile. Fresh urine is sterile, safe, and it works wonders.

The even easier option for making leafmold is to simply scoop leaves up into garbage bags. Fill the bags three-quarters full, tie them closed at the top then puncture holes into the bottom and sides to allow its contents to breathe. Place the bags out of the way and forget about them for a year or two.

Using Leafmold in the Garden

After one year most leafmold can be crumbled by hand and while it won’t be fully broken down, it’s good enough for the kitchen garden. Use it as a mulch around existing crops and fruit bushes, dig it in to improve the condition of your soil, or just leave it on the surface over winter for the earthworm population to dig it in for you.

Leafmold that’s a couple of years old will have a finer texture similar to the compost found in garden centres. By this stage it’s unlikely to show any traces of the original leaves. This beautiful, friable material can be used as above or as compost for seed sowing. Alternatively mix it with equal parts garden compost, sharp sand and good-quality garden soil to make your own (free!) potting compost.

By Benedict Vanheems. Photo credit-Leafmold bin: Far Closer, Rake with leaves: Wickenden

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Comments

 
"I rake up our leaves and shred them before piling them up for the winter - shredding them helps speed up the process considerably. I also just like using shredded leaves as mulch - it is just as attractive as bagged mulch, a great weed suppressant and free!"
Dorian on Friday 7 October 2011
"Every Fall,we shred leaves by running the mower over them. We put about 4-6 inches of this material over the raised beds after the first hard frost (worms move deeper during this period). We then use a mini cultivator and till it into the top 6 inches of the beds, not harming the worms.Finally, we top the beds with 2-3 inches of finished compost or mushroom manure and top with clean straw till spring"
tj on Sunday 9 October 2011
"I have always put my new fallen leaves into flower beds and around plants that can use the winter protection. At the end of winter they are wet and on their way to being decomposed. So. this year I think that after I take them out in the spring I will put them into my compost bin. At that point they are half way there, right? "
Gail on Tuesday 23 October 2012
"Hi Gail. That's right, after a winter in the elements they'll certainly be softened up and well on their way to decomposing. If they aren't hindering growth of ground cover plants, you could always keep the leaves where they are, moving them to around your plants rather than on top of them. The worms will eventually 'dig' them in for you and recycle the nutrients into the soil. "
Benedict Vanheems on Tuesday 23 October 2012
"Can I MIX old brown beech leaves (collected in spring when new growth pushes them off) with new green leaves cut when we tidy the hedge in August or do we need two piles???"
Clare Hodgkinson on Wednesday 12 June 2013
"Hi Clare. You can indeed mix beech leaves with new green leaves - that is fine. The green leaves could also be added to a normal compost heap to contribute their goodness."
Benedict Vanheems on Thursday 13 June 2013
"Hi, thanks for great info, I am new to composting and such, so thought I would start with leaf mold. Can I add deadheaded flowers as well as leaves or does it have to be just leaves? I have roses, but most of them suffer from black spot at times, can I still use the leaves from the roses or should I leave them out? Will the spores survive years in the bin liner I am going to use? Thanks for your help!"
Helene U Taylor on Tuesday 21 January 2014
"Hi Helene. You can add deadheaded flowers, although the more non-leaf material you add the more the resulting product will look and behave more like compost than leafmould. I would shy away from adding black spot-ridden leaves however, as the cool rotting temperature that defines leafmould may not kill off the spores. This would then make your leafmould a potential cause of a new outbreak of this disease. I'd add black spot-infected leaves to a hot compost bin where a quicker rot and warmer temperatures generated by the decomposition process will kill off the spores."
Benedict Vanheems on Tuesday 21 January 2014
"Thanks for your quick response, a few more questions: -All descriptions of how to make leaf mold talk about collecting dead leaves from trees, but can I use any kind of leaves? -And can I use green, fresh leaves? They will of course wilt in a few days in the bin liner, but will green leaves pruned from my various kind of plants create a different environment than leaves already dried and dead? -I have a garden with typical acid loving plants, can I add needles from my thuja (western redcedar), to make an ericaceous leafmould? -When I prune plants, can I add the whole plant, or do I have to pick off just the leaves – for example when cutting down my peonies, clematis, ferns and lilies in the autumn, can they all go into the leaf mold bin, just chopped up in pieces? I don’t have a compost bin, I really have nowhere to put one in my tiny garden, but I collect my garden waste and the council get it for their composting so it doesn’t go to waste. I will continue to add the waste from the roses to that bin so the council can carry on dealing with that. But I think making leaf mold will be possible in my garden, as I would just add and add to it and not need to turn it regularly – and when the bin is full I just leave it until it has developed into leaf mold. That’s the idea at least! Thanks for your help!"
Helene U Taylor on Tuesday 21 January 2014
"I read that maple leaves are especially good for vegetable gardens, and that oak leaves are more acidic. is this true? Are there any leaves we should avoid in terms of pH, etc.? I ask my neighbors' lawn service to dump the leaves they collect rather than haul them away, and I used them as mulch, and to improve the soil. I don't want to add the wrong things to the soil. Are most "thin" leaves good? Any to avoid?"
Suzanne on Thursday 5 November 2015
"I have found leaf mould excellent in the garden and flower beds. If you can find someone or a place where someone has dumped leaves for possible years, you have found a gold mine. We had a beach cottage and leaves were dumped over a ditch. They had turned to soil which was black and smelled so earthy. Best garden we ever had that year. You might find looking around abandoned old farm houses will have a pile."
joan on Monday 9 November 2015
"Hi Suzanne. Any leaf can make leaf mould but some rot down much quicker - oak, alder and hornbeam for example - than others. Thicker leaves like sycamore, beech and chestnut take longer to rot down - though you can speed up the process by shredding them first. As far as pH goes, pine needles tend to make an acidic leaf mould. It is best to make a separate leaf mould from pine needles, which can then be used around acid-loving plants such as blueberries. Other conifers take longer to rot down but can still be used to make leaf mould. "
Ben Vanheems on Monday 9 November 2015
"Should leaves be compressed or does this remove too much air from the rotting process?"
Betty on Monday 16 November 2015
"Hi Betty. There's no need to compress the leaves - they will naturally slump down into a denser clump with time. However, if you need to fit more leaves into your leaf mould pile/bags then there's no harm in pressing the leaves down to fit more in."
Ben Vanheems on Monday 16 November 2015
"Fantastic tutorial. Thank you. I tell my wife that autumn is a great time, she thinks its because of the wide range of fall foliage, but we as gardeners know it's because we are about to get loads and loads of leaves to use as compost in the garden :)"
Michael C Podlesny on Friday 6 October 2017

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