It will kill annual weeds but not the likes of nettles and docks. Better to dig these out.

i agree with moon_grower there, on my allotment i use black plastic pegged down to kill weeds untill spring time but perennials i dig out first.

Right. As the old saying goes "One years seeding equals seven years weeding." It is better to pull or hoe them out.

Personally I do not hold with using black polythene to suppress weeds. I still do not think it is good for the soil, as Eclectic says above it warms up the soil when it should be experiencing the freeze thaw cycle which helps to kill of pests. Digg over and remove the perennial weeds and then let mother nature get on and do her job.

its better to use weed supresseing membrane because it still stops the weeds after you dug the mane ones out and doesnt hurt the soil like black polythene . also later on you can obviously reuse the membrane .

If its an area you can leave unattended for over a year, and you apply thick, black polythene sheeting (not thin bags) anchored down round the edges, it will kill everything beneath if left long enough, including bramble roots. But it cannot be less than a year, and the polythene must be thick to exclude all light, air and water.

thats what i thaught bamboo but moon grow said it hurt the soil ? x

To some extent, that's correct - life extant so to speak, but it revives once uncoveredm dug and humus added, and air, light and water penetrate again.

Why kill everything else in the soil when you can use the old fashioned method of removing the weeds, digging everything over and mulching is my view NP but each to there own.

Well, depends on the circumstances, MG - I had a relative who bought a massive place in acres of land in Devon years ago - there was a walled garden full of wild brambles and other stuff and they just didn't have the time to do it straight away, with so much other land to be sorted. So they used the polythene trick, and 18 months later, when they finally had time, sorted it out then. Everything dead, walls rebuilt, soil refreshed and revived, peach trees in against the walls, fabulous 2 years later.
But not recommended otherwise.

I used it on a new allotment very successfully - things grew perfectly well afterwards so any soil damage there might have been didn't affect the plants to any noticeable extent. There was just no way I could have dug it over in the state it was in. A farmer friend gave me some of the heavy duty stuff they used to wrap haylage in. Other people use old carpet - unsightly but it does the trick.

well thats what i found personaly but as bamboo sais theres different reasens for needing black polythene . old people for instance or disabled or as i did to kill some very difficult bamboo .

Bamboo might be difficult sometimes but we don't need to kill her...lol

LOL! I bet there's a few been on here over the years who'd quite like to kill me off;-))

dont look at me lol x .

Not me - you're far too valuable!

lol x .

;-))