[NellyCB]

I have a couple of patches of ground on our allotment that I wish to cover with a black plastic for a year or so.  I'm struggling to source some big sheets of plastic - what else could I use please? 

[arugula]

Try some of your local builders merchants to see who stocks Visqueen - either DPM or silage pit sheeting, AKA big sheets of black plastic. 

[NellyCB]

Try some of your local builders merchants to see who stocks Visqueen - either DPM or silage pit sheeting, AKA big sheets of black plastic. 

Great ta. Will have a look

In the meantime, is there anything I oculd recycle or make use of for free or v v cheap?

[arugula]

How big is the patch of ground? Would it be too big, for you to buy some black bin liners and cut them open on two sides? Tedious, I appreciate, but cheap. 

[NellyCB]

How big is the patch of ground? Would it be too big, for you to buy some black bin liners and cut them open on two sides? Tedious, I appreciate, but cheap. 

Yes it would be a suitable size - good thinking.  I suppose if I got the nice thick sort they'd be sufficient wouldn't they?

[arugula]

Probably, if you fix them down well enough. 

[Salmo]

You can buy heavy duty plastic sheeting from most builders merchants or agricultural suppliers.

Personally I would never cover soil for a long period with sheeting that did not let water and air through. It cannot do the soil micro-organisms any good and will elliminate any worms.

Harrods Horticulture and many others sell weed control fabrics at less tha £1 a sq metre. Probably cheaper than polythene bags.

http://www.harrodhorticultural.com/HarrodSite/category/Garden+Netting_Ground+Cover+and+Mulching+Fabrics/

Why not take the opportunity to sow a green manure mix, something like italian ryegrass and clover, which you can dig after a year to improve the soil structure. Covering it with plastic will leave it pretty impoverished.

[Plottered]

what about cardboard....thats what im using at the moment on a few raised beds...its available from lots of places and when it starts to rot down just put more down. I wont be leaving it down years though, and when im ready i'll fill up on top of it with soil and muck etc.

[Yorkie]

That would be fine, so long as it looks tidy-ish or you run the risk of warning letters.  You can plant through it too 

[bigben]

what about old fashioned weed fabric? This lets water thru so is better for the soil and if you get the thick stuff is as good as the plastic. Plus when you are ready to start to plant you can cut holes thru and grow stuff or put bags on it to grow spuds. I have found this stuff pretty good and you can buy in smaller or larger amounts. I am sure others will provide suppliers that might even be cheaper.
http://www.amazon.co.uk/Heavy-100gsm-metre-Control-Fabric/dp/B0021GA88K/ref=sr_1_15?ie=UTF8&qid=1314366363&sr=8-15

[Totty]

You could speak to a local haulier or similar and see if they have an old tarpaulin you could have. Very heavy duty

[Plottered]

What about putting green manure in....would have the added benefit of doing the soil good.

[Poolcue]

I use an old ground sheet