Weed suppressing membrane or not?

[ritchie111]

Hi
I am looking for some advice really.
I have recently leveled the allotment and i am thinking about covering it with weed suppressing membrane then building raised beds and a poly tunnel on top of the membrane. The reason of covering with membrane and adding raised beds is because the soil/clay is not the best to grow stuff in.
Whats are peoples opinions on this please. Good idea or bad?
Cheers Ritch

[Veggielot]

Its good to surpress weeds particularly in the areas you are using yet. I would consider removing from the raised beds as you build them to make it easier for worms to get into the bed unless you have a real problem with weeds.

[mothhawk]

If the clay/soil you have is not good for growing, then you won't have many weeds and don't need a membrane cover If it is good for growing, there will be lots of weeds, BUT you really want your plants to get their feet into that good stuff (and usually with a bit of attention clay is good stuff).

Dig in lots of organic manure, a bit of coarse grit (NOT sand), pick out as many weed roots as possible, then put your raised beds on top. Instead of having a max of the height of the raised bed to grow in, your plants will be able to get their feet down, and draw up water and nutrients from a much greater depth. Some vegetables can send fine roots down 3 feet if the soil is workable enough.

[Scarlet]

Also if you use membrane under the beds you won't be able to grow lovely long parsnips!

[LincolnshireFloyd]

It sounds like a good idea if you have plenty of time and plenty of water to stop the raised beds from drying out. It will be extra work but if you enjoy it why not.
If you are going to import a lot of soil for your raised beds why not just dig out the areas you want to grow in and replace the soil at ground level? That way you avoid drying out your growing areas. I know what clay soil can be like when it's wet, sticks to everything including you so a membrane on your paths with a wood chip covering would be user friendly. Not sure about poly tunnels. They always seem to go to extremes of temperature.

It's going to cost you time and money to get it sorted out but once it's done your gardening will be a permanent pleasure rather than a battle against the conditions. Nothing can beat a nice easy workable garden.

[Alison]

I'd never put it under the beds and tunnel as I'd want as much depth as possible to grow in. However it's very useful in path areas.

[cazp]

I loosened the clay soil under my raised beds and lined the bottom with old cardboard boxes in preference to membrane. I thought this might help stop any existing weeds coming through but would also allow the worms in. Seems to have worked as that was 1.5 years ago and weeds havent been a problem but the beds are packed with worms.

[Two_Sheds]

the soil/clay is not the best to grow stuff in.

What makes you think that, Ritchie?

What weeds are growing in it at the moment?

[PyreneesPlot]

After three years my clay soil is lush.
It started off as just clay (no soil)- indeed, Mr PP has just used a load of the unimproved stuff to line a pond! Just keep adding organic matter to it and don't stand on it!

[kathyd]

I've got membrane fabric under some of my raised beds, which have about 10-12" soil in them. I've grown most things in them - potatoes, brassicas, parsnips, sweetcorn etc - and they've all grown without any problems so far... granted my parsnips were 'only' 10" long, but then again I didn't even know I liked parsnips and I'd forgotten I'd planted them until they popped up, so I didn't really mind!

The beds seem to get plenty of worms in, no idea how - probably from addition of home-made compost? - but I have to say that the weeds still find their way in there, either through donated soil (do you have any idea how much soil you need to fill a large raised bed???), or sheer determination. My foe this year is the bindweed coming back - as TS said in another post elsewhere, fabric just pushes it out sideways to find the edge, and then it's back with a vengeance. So unless you really can't grow in your soil (and our clay in Leeds was lovely and rich, although hard work), I'd maybe consider the cardboard option Cazp suggests above rather than more permanent fabric?

[Stacey Steve]

I build raised beds with membrane paths covered in chippings. I did however get weeds growing at the edges. As I never stand on the beds, so they do not become compacted, I find that keeping the weeds from encroaching into the beds manageable, even dandelions pull out clean and whole.
The only problem I now have is that the chippings compost down over time and then weeds grow on the paths, most are quite easy to pick off, but there are some that do root down through the fabric.
I would advise you to use non woven fabric as opposed to the heavier woven type. The woven strips threads all the time unless you have cut it with a hot blade in the first place and of course weeds can still come up through the weave.
The fabric has worked fine on one of my plots where it is all raised beds and paths but I made the mistake of covering vertually a whole plot that I use as an orchard.....Oh what an error, am gradually removing it now and believe me it is hard work. Didn't help that all this plot was done in woven fabric
I would strongly advise not to cover under your raised beds, with the best will in the world, when you are digging (unless they are really deep) you are going to penetrate the membrane and keep getting caught up in it.

[ritchie111]

Thanks for some great advice from everyone. I am now going to re-think the membrane idea of covering the whole garden and just using it around the paths. I initially thought with my allotment been so big the membrane would be an easy option to keeping on top of alot of weeding, another reason for the membrane and raised beds is because the soil is very clayey, ashy, full off small gravel and acidic.
The Raised beds i will be putting in with a variety of depths which will cover most vegtables.
Cardboard in the bottom of the raised beds is another good idea as suggested in some comments.
So my plan is this, cover the whole garden with membrane put the raised beds in, then cut the membrane inside the raised beds, add cardboard and fill with good topsoil?
What do ya think?

[veggiechicken]

I think you have more money than you know what to do with!! Covering everything with membrane then cutting holes in it

[rustylady]

Me too VC. You're going to waste an awful lot of membrane Ritchie. And for goodness sake don't get the cheap stuff - it's useless.

[BertieFox]

First, get rid of the idea that a membrane and new soil or compost will eliminate all your weeds. Weeds will always come back no matter what you do and the more fertile and better your soil, the more weeds will grow in it.
Second, there's no such thing as an 'impossible' soil, other than solid concrete or rock, and clay is in fact very fertile and potentially an excellent soil. It just needs lots of organic matter and breaking up.
As others have suggested here, I would try going for the 'deep mulch' method, cutting down all the weeds, covering the ground with cardboard from the tip or skip (which you make very wet)and then covering over compost, straw, grass clippings, mushroom compost or whatever you can get hold of. This will enable you to grow anything that you can plant out as long as you are able to water in the first year.
Perennial weeds will still come through eventually, but you can spot treat them or dig them out then. Weed suppressing membrane is expensive, made from unsustainable materials, and of limited life.
In other words, make use of the soil you have and just improve it. That is the permaculture approach which says see every problem as a potential solution and try to make the most of what you have rather than buying in external materials.