Plastic covering on plot - is it a good idea?

[john9159]

Would you say it was good practice to cover an allotment plot with thick, non-permeable plastic sheet on a large area?

I'm not convinced it is as it may cause the soil to bake dry if left for a long period or even putrefy if it was wet to begin with.

What say you?

[Dynamo]

I cover as much ground as possible during the winter, that way its weed free for when I prepare it in the spring. It makes digging the plot so much easier. I don't see the problem with covering it in the summer too if you don't have anything to plant in it. Personally I'd find something to plant there though, even if its just a green manure crop.

[Kristen]

What say you?

Depends

For a plot being got under control, and to stop weeds growing / kill them off in the meantime, its a reasonable idea. No water will get through, which is not so good (compared to a woven weed suppressing membrane, but that might not exclude enough light to kill existing weeds)

As a mulch under existing (desirable) plants I'd definitely be against it (but I would use woven weed supressing membrane) as it lets neither air nor water through.

It is what we used to do in olden times, before woven weed suppressing membrane existed. (Usually only the width of a "row" though, so perhaps 4' wide.

[veggiechicken]

How long would it be covered - and why?
I'm guessing that someone on your site has done this and you're looking for reasons why it shouldn't be done?
What do your rules say?

[Greenleaves]

Just for interest our site rules state that weed suppression materials may only cover 10% of your plot under normal cultivation and 30% in the first three months.

[Kristen]

Just for interest our site rules state that weed suppression materials may only cover 10% of your plot under normal cultivation and 30% in the first three months.

I've grown vegetables for 4 decades, only ever in my own garden, and last year experimented with woven weed suppressing membrane on my beds (raised beds,4' wide) for the first time. They saved so much time weeding, reduced the irrigation down to zero on many crops, and significantly reduced on the rest, and I think I have had better crops too, that I am going to increase membrane to 100% of my beds this year. Wouldn't be very popular with your allotment secretary!

That said, I suppose I could mulch over the membrane, and maybe that would keep them happy (or they wouldn't notice it!!), but because I rotate my crops I didn't do that (messy to get the membrane up at the end of the season) and I mulch under the membrane instead.


July 2014 - experimental strips of weed membrane

[Alison]

Just for interest our site rules state that weed suppression materials may only cover 10% of your plot under normal cultivation and 30% in the first three months.

I use mulches to suppress weeds, is that OK or is that seen in the same manner? Seems a strange rule unless it's further clarified to mean in areas with no crops. 3 months seems pretty tight too, I got my plot in late August one year, only had time to cut it back and start tidying before winter hit. Most of it was covered until late the following Feb / March and I could only cultivate about 60% in the first year due to the state it was in. People were pretty amazed I managed that much so quickly. I also had a reasonably large area covered in cardboard (a type of weed suppressing material) with potatoes growing through. Got a great crop and have recommended this approach to a lot of people since. Sorry if I sound like I'm ranting but poorly thought out rules really wind me up and is the main reason I'd do my best to resist any form of committee ever being formed on our site.

[john9159]

IMO mulch is organic matter (such as spent hops), allows air and water to permeate and can be dug in when it's served its purpose, which is to suppress weeds.
I am referring to solid plastic sheet which deprives the soil of everything and would like to know how this affects soil or indeed does it do any harm at all.

[Snadger]

We covered a whole plot with black impermeable visqueen which we were going to use this year for our community plot.
It did its job and killed everything but the sunlight degradation took its toll. It cost us 40 quid-ish and was trashed.
At least the new plotholder has a clean plot (after a change of plan), but with rents being only £45.00 it wasn't really a viable alternative long term!

Looked blinkin awful when it was down as well!

[Muppet194]

I've had plastic sheeting covering part of my plot since about November time, I peeked under it yesterday to see how the ground looked. There were still surviving dandelions, all be it weak and feeble , but a gazillion slugs. I removed the sheeting to allow birds to pick them off. Dont think I'd use non-permeable plastic again, I'll sow a green manure.

[Greenleaves]

I think they reasoning is that people take on plots and cover the area with all manner of things and then never return. One plot recently was cleared of 30 doors. No one really takes much notice, it is just one of those rules the site has.

The rules are set by the council, but no doubt the site reps have input

[Coopers]

Hi, i covered chunks of my plot in my first season to save me being overwhelmed. It did the trick. I'd do it again if i find sections are unused with loads of nettles. I dont get an awful lot of time at allotment due to work so it helps me keep on top of it until i get better.

[snakeshack]

I think non permeable sheet is a bad idea as it prevents water entering ,it will undoubtably kill the weeds if left long enough though.
woven membrane lasts longer,lets the rain through,and kills the weeds and if bought in large quantities is no more expensive,it also does not degrade as quickly in sunlight .
polythene sheet breaks down in sunlight leaving loads of bits to pick out of the soil later.
cardboard is better still,it stops the weeds can be mulched over with straw,wood chip,compost or manure and breaks down over the year,improving the soil.plus its free.

[marchogaeth]

I have used what was sold as "garden grade" black plastic on my ground to produce a total kill of couch, docks, creeping buttercups, nettles, pineapple weed and it has done a really good job. This was after buying weed suppressing membrane which did let too much light through.(I am just starting to throw some pieces out after three years but mostly because I have finished with them, they would do another year or two I think.)

After reading advice on here, I weighted it down so it couldn't flap up and down and create a hard soil surface. The polythene was down for at least 9 months and I didn't try to grow through it which had also been my mistake with the membrane.

My soil is pretty wet all the time (slope in Wales - run off!)

I did not go straight into cropping on most beds, when I took the plastic off but built a pile of compostables - greens/hay/muck and put that under cardboard for several months. The reason being that my neat soil is very high in clay and very acid.

On the bits I did crop, I did a fairly light dig (3/4 spade depth) and then forked/raked it to a tilth and planted. I did remove any nettle/couch roots I found just to be sure. I fed the crops well and used lawn mowings etc as mulches through the year.

Slugs can be a problem under any covering but I often found toads under there as well. And once the plastic was lifted the birds soon made short work of the eggs.

I really don't know if I would do it again as I am now committed to cardboard but it would have taken two or three applications of board to do the job the plastic did in some places (cardboard is not what it used to be!).

It really depends on what you want it for.

[Monster]

I got my first plot late last spring and it was a tip - 5-6ft perennial weeds on half, the rest was rubbish a nd waist-high grass. I managed to clear half of it before winter and just covered most of the rest with black weed suppressing membrane for the winter, which did an ok job at weakening weeds, but honestly I'm not going to use it ever again, because some of it came loose over the winter and just shredded in the wind. Some was held down with bricks and tires, some was pegged down with tent pegs - didn't make a difference, got shredded where the wind caught it. So not only is it now useless but there are long strings of plastic all over my site which I've had to clean up.

Also the previous owner used it, along with carpet and must have mulched over it or something. I have the pleasure of pulling it all up from under several inches of soil and weeds

Cardboard was much better, it didn't blow away and rip in the wind, killed the weeds just as effectively, I don't have to get rid of it, and there were lots more soil creatures under it.