How to make a Loam Stack

I mentioned this subject earlier this month, in an article about how to lift turf the "easy" way: and a surprising number of people asked for more information on Loam stacks.

Simple explanation: a Loam Stack is nothing more complicated than a pile of lifted turfs, stacked neatly, and left to rot.  "Loam" is a fancy horticultural term for "soil of so lovely a texture that it makes your teeth itch in envy." 

Technically, "Loam" is the perfect blend of soil particles of different sizes, resulting in a product which is:

- friable, ie easy to dig and turn over: 

- nutritious, ie contains organic matter

- of good texture, ie has a mixture of smaller and larger particles

- retains moisture well, ie does not dry out into dust, or crack like concrete

- is a pleasure to handle.

It is, in fact, a sort of holy grail for gardeners: we all wish that we gardened on good loam.... but any garden soil can be improved, and making your own loam is a good step in the right direction.

How to Do It:

When you've just extended a bed or border, you'll find yourself with a pile of left-over turfs, and the question is always, what to do with them? They are too big and solid to go on the compost heap, obviously, but it seems a shame to put them in a skip, or in your green waste wheelie bin.

If you have any bare spots in the lawn, or some ragged edges, you can use a few of them to patch and mend, but generally speaking, most turf-lifting jobs leave you with a couple of barrow-loads of leftover lumps of turf.

So, let's be ecologically sound, and make them into something useful!

Find a corner of the garden, out of sight preferably, and make a neat free-standing stack: start with a layer grass-side down, then a layer grass-side up, then a layer grass-side down, and so on. Lay the chunks of turf down in a sort of brick-work pattern, as this helps to hold the stack together.

Try to keep the edges straight and as upright as you can (there is a terrible tendency to make each layer a bit smaller than the one below, but if you do that, you end up with a pyramid), and make an effort to keep the outside edges higher than the middle: that is, don't let it droop off at the outsides.  Use the thicker lumps of turf for the outside, thinner ones towards the centre, so that any rain which falls on it will be held in the middle of the stack, rather than washing off the outer layers.

Here's one I made last week:

It's tucked away out of sight, it's six inches clear of the wall, to avoid damage to the wall: and it's in the open, so it should receive a fair amount of natural rain.

I have another section of grass to lift next week, so it's not quite finished yet, but you get the idea.

Some of the questions were:

"How do you know how big to make it, when you start?"

Oh, good question. 

It's a guess. You have to guess. I could say that I looked at the area whose turf I was about to lift, calculated the square footage in my head (as "one" does), calculated the optimum base size, based on that square footage, then started my loam stack accordingly.

But I'd be lying. *laughs*

I guessed.  Sometimes I end up with a wide, low loam stack: once, I got it completely wrong, and ended up with a Towering Inferno (but without the flames) which gently topped over, six months later. That was annoying. 

"How long does it take to rot down?"

Quite a long time - usually two years. That's another reason for tucking them away in odd corners, so you aren't tempted to break them open early, just because you are sick and tired of looking at them. Many books, and most of the internet, will say "6 months to a year," but I have found that two years is more realistic, and the longer you leave them, the better the material. If you break them open too soon, you find that you still have quite a lot of fibrous rooty material, which means you feel obliged to sieve it, or at least to sort through it and discard the most fibrous bits. As you will know, dear reader, from my many, many articles on the subject of compost, I hate "faffing" ;  I would far rather take a bit more time and allow it to happen naturally, than to add chemicals (or physical exertion) in the hopes of getting my compost a bit sooner. And the same goes for leaf mold, and loam stacks: let them sit! Don't rush!

"Why do you have to stack the layers alternately green side up, green side down?"

Another good question.  I have no idea - it's "always been done this way". And anyone who knows me, will know that I hate doing things just because they've "always been done that way", but this is one instance where I actually do it the accepted way, without questioning it.

Logically, you could just as easily put all the layers green side down: the important part is to exclude light, to ensure that the grass dies off, so theoretically, they don't actually need to be stacked alternately. But for some reason, I have never minded doing it this way, so that's how I do it, and that's how I teach it.

 The only important layer is the top one: you don't want the final layer of turfs to be left green-side-up, otherwise it will just grow: and if you find that the alternating stacking leaves you with green-side-up, then just put the final layer green side down, regardless of what the one underneath was doing.

"Can you add to a stack, once you've started it?"

I prefer not to:  otherwise you end up with some parts being more rotted than others, or - more to the point - you miss out on having access to the older part, because it is covered up by the newer layers. 

Talking of adding to stacks, here's a Crime Against Horticulture from last year:  I'd made a beautiful neat, small loam stack in this garden:

 

 

Again, it was 6" away from the wall, to avoid damage and damp, nice and neat, free-standing etc.

Then the workmen came in to widen the drive, which meant lifting quite a lot of the grass.

My Client told the workmen to stack their lifted turf on my loam stack.

And this is what they did:

Hmmmmmm...

Instead of stacking the turfs neatly, they just tipped the lot in a pile, on top of my beautiful stack.

And they piled it up, against a dry-stone wall... soil is heavy, you know.

We had to dig it all out, to avoid damage to the wall, which was quite annoying!

"Do you need to put a plastic sheet underneath it?"

No, that's not necessary: it's better to have it on soil, really, because then the worms can work their way up and down the stack, thus helping it to convert into loam.

Do bear in mind that if you start a loam stack on top of a mass of ivy, or bindweed, or Ground Elder, etc, then you may well be laying problems up in store for yourself, because the bottom layer of the stack will become infested with the perennial weeds, which is bad!

So, starting the stack on bare soil is preferable. 

"Why bother?"

Why, indeed? Well, because you are taking part of your garden which you are, in effect, discarding, and turning it into something wonderful: top quality loam, which can be used for potting up, for growing seeds, for putting plants in pots (ie decorative pots), for spreading on the soil as a mulch in spring, or in autumn: for topping up odd holes or low areas, for enriching a planting hole: all sorts of uses!

And instead of having to pay to have it removed from your garden - ie putting it in the green waste wheelie bin, a service for which we have to pay (well, we do round here!),or a trip to the dump using your petrol and your time - you are creating a product which you would otherwise have to buy.

It's like a savings account for your garden: put old turf in, wait a while, then get lovely loam out!

It's ecologically excellent: you are retaining organic matter in your garden, which is beneficial because it is full of the microbes etc of your own garden, and is therefore "familiar" to your plants, plus you are avoiding the risks associated with buying in topsoil, organic matter, or soil conditioner, ie the risk of bringing diseases or unwanted weed seeds in: and, if you really need another reason, you are not bringing in a batch of "alien" microbes etc, which will then have to be assimilated into your garden's ecology.

Best of all, apart from the labour (and you were going to lift it anyway, so why not stack it neatly?), it's free!

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