Black plastic sheeting

I got the keys to my allotment a month ago, and now am wondering about putting some of the black plastic sheeting down. Is it a specific grade and can anyone tell me of a cheap supply, please? Is it just to keep the weeds down? Thanks, Liz

 

I don't think there is a specific guage, but it needs to be reasonably thick to last and to be opaque. It will keep weeds down by excluding light.

I bought some white polythene sheet a little while ago - and its not as cheap as you think it should be. I have just Googled and come up with this. http://www.allplaz.com/acatalog/4mtr_x_50mtr_x_125mu__Heavy_duty_500gauge_.html

You could try a builders merchant, or similar. Thick blue plastic sheet is often used on building sites. It will do the same job. I bought some a year ago and it was cheaper than DIY shops.

 

damp proof membrane comes in 5m x 5m, and is ideal.

 

The problem with plastic sheeting be it black, white or blue is that it doesn't allow water through and all the rain we are getting now has to go somewhere so it runs off creating a waterlogged area.
The woven membranes ( Mypex, Phormisol, Terram ) allow air and water through whilst still supressing the weeds. Also not as stiff so easier to fit in place and to roll or fold for re-use. Good stuff can be used for many years.
Try a horticultural suppliers or builders merchant

 

I think the problem with textile fabrics is that as well as letting water through they also let light through. For them to be effective as weed suppressants you have to cover them with a layer of something, be it gravel or wood chips etc, to exclude the light. Weed seeds can also germinate above the fabric and grow down through it.

Old carpet would exclude light and allow water through, but it is only practical on a small area.

 

Good point about the run-off, Lovage. I didn't want to invest too much money this first year, in case I find I can't spend the time there that I want. I will look at the woven membranes though. We aren't allowed to have carpet on the allotments.

 

I've used thick brown woven membrane that 's been in place for 3 years now in a strawberry bed with no weeds coming through.
You can also get black plastic sheeting that has very tiny holes in it to let water penetrate. I've used it for the past three years on my brasicca bed. Only prob is is that it very thin and you only get one year's use from it. It's pretty cheap though and really works well.