Allotment Gardening Advice Help Chat

Growing => Grow Your Own => Topic started by: Chappers on May 26, 2009, 16:11

Title: Black plastic for weed control
Post by: Chappers on May 26, 2009, 16:11
Does anyone know how thick black plastic sheeting needs to be to be effective as so many thicknesses are available.

cheers Paul
Title: Re: Black plastic for weed control
Post by: woodburner on May 26, 2009, 16:31
Bin liners are too thin. Hold it up to the sun, if you can't make it out, well that's as good as it gets, light wise. You can probably get away with a bit thinner, but thicker is likely to last longer, as long as it's UV stable and flexible.
Personally I use opened out cardboard boxes these days, I'm a terrible skinflint.  ::)
Title: Re: Black plastic for weed control
Post by: Kristen on May 26, 2009, 16:33
Do you want plastic sheet, rather than weed suppressing fabric?

Plastic is solid, water and air can't get through, weeds can't get out!

Weed suppressing fabric is a mesh, water and air can get through, MOST weeds can't get out.

Plastic might be used for clearing a plot initially (e.g. instead of weed killer), but I think weed suppressing fabric is preferred for pretty much anything after that.

Sorry, don't know the "grams-per-square-metre" that gives you something that keep the light out, weeds down, and you can, for example, walk on without puncturing.
Title: Re: Black plastic for weed control
Post by: Chappers on May 26, 2009, 16:42
im after plastic sheeting as the membrane is designed to be used under gravel or bark and will still let light through if its not covered.
Title: Re: Black plastic for weed control
Post by: Kristen on May 26, 2009, 17:09
Mypex (woven weed suppressing fabric) supposedly has less than 1% light transmission and is UV stabilised ...

I have bought plastic pots, hose, etc. from Plastics by Post and they've been very helpful.

Hopefully this link will take you to the right place, they have Woven, Non-woven and non-Porous products (should be listed in a menu in the left pane)

http://www.plasticsbypost.net/mainpages/weedcontrolpage.htm
Title: Re: Black plastic for weed control
Post by: Yorkie on May 26, 2009, 17:35
Most membranes do not let enough light through to be a problem, I think the reason they say to use them under mulches etc is rather to do with UV stability.  If the covering is due to be down more than a month or three, your soil will benefit vastly from the membrane rather than the plastic, as Kirsten said.
Title: Re: Black plastic for weed control
Post by: celjaci on May 26, 2009, 18:25
The woven type ( Mypex, Phormisol, horticultural ground cover ) is best under gravel or bark as it allows water to drain through.
Same stuff is often sold by builders merchants as 'Terram' although this name used to be used for a  white, non woven landscape fabric
There are several weights available ( need to check when comparing prices )
Average is 100g/m2
Title: Re: Black plastic for weed control
Post by: Babstreefern on May 26, 2009, 19:30
I used all sorts on my plot to get rid of the weeds.  I had crouch grass and other nasty weeds.   First of all, I borrowed someone's petrol strimmer and strimmed everything down to ground level; I then sprayed weed killer all over, and then used all types of weed suppresent plastic, normal plastic, we even used one of those blue trailer covers from B&Q, a ground sheet that was past its sell by date that we had been using for camping, carpet (not the foam backed ones).  We eventually covered all the plot in May of last  year, and left it alone until August/September as we had the other half of the plot that we were growing stuff on. We then started uncovering it bit by bit, first raking off the dead stuff on top, and digging over the soil, picking out any roots.  We had it lovely and clear by November, when we left that plot to swap with another (I could have wept :().  It was my hubby's idea not mine.  Anyway, I've not been on for a week or so, but this weekend, I came on and looked at our old plot, and it was absolutely covered with another type of weed - looked like chickweed to me.