Weed suppressing membranes

Weeds are the bane of gardeners’ lives and are especially a problem on any bare areas of soil, such as veg beds, left empty over winter. 

Weed membranes -sometimes sold as weed control fabric - act by blocking light and thereby preventing the germination of weed seeds so you don't need to use chemicals to control them. There are several types available, including woven black plastic (sold as Mypex and Groundtex), non-woven polypropylene which resembles thicker, dark-coloured horticultural fleece, and eco-friendly options made from paper, wool or jute. Some gardeners also turn to free options, such as old compost sacks or cardboard. 

The Which? Gardening magazine researchers wanted to find out which ones would do the best job of keeping weeds at bay. 

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Recommended weed membranes

Non-woven weed control fabric

Pros Effective, reusable with care
Cons Contains plastic

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We found both easy to cut cleanly and to push black plastic fixing pins through. We also tried fixing the G100 with metal staples, but these caused the fabric to tear at the points where the staples go through. Both products kept weeds at bay, and the two plots had only 5% weed coverage at the end of May when weeds were growing strongly on bare soil. The thicker material warmed the soil by around 2°C above the temperature of bare soil. Both fabrics were intact at the end of the trial and could be reused. 

Woven anti-weed fabrics

Pros Very effective
Cons Prone to shedding plastic threads

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These are easy to cut with strong scissors, but strands fray off cut edges, leaving strips of plastic in the garden that can get tangled round machinery. You need to cut slits in the material with a knife to push through the barbed plastic ground pegs or to plant through. Both products completely prevented weed germination and raised the temperature of the soil by a few degrees above bare soil temperature. They were durable and could easily be reused. 

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Pros Effective, reusable, environmentally friendly
Cons Pricey

This sturdy material has a low carbon footprint and is fully compostable, leaving no synthetic residues. It was easy to cut and peg down and felt substantial and slightly woolly. The soil under the membrane remained moist and was 3°C warmer than bare soil. By the end of May there was a smattering of weed growth under the membrane, and the material itself didn’t show any deterioration so could be reused. 

Others on test

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Pros Biodegradable
Cons Not durable, tricky to use, rips easily

Mulch Organic

This thick and rather rigid material proved tricky to use. The paper ripped in several places just three days after laying it, and we found that water pooled on the surface rather than draining through to the soil. It was held down with metal staples plus a border of soil, but this didn’t prevent it being blown away in the wind; we had to replace it three times during the trial after high winds and heavy rain. There was around 20% weed coverage on the plot at the end of the trial.

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Pros Durable, eco-friendly, biodegradable, easy to use
Cons Pricey, birds like it too

We really liked the look and feel of this product. We pinned it down with the suggested bamboo skewers, which were far smaller than they looked online - more cocktail stick than tent peg - but this didn’t matter as the wool felt melded itself to the soil and was unmoved by high winds. It did a pretty good job of keeping weeds at bay; we found only 15% coverage on the plot. Unfortunately, birds liked it, too, pecking off tufts to take away for nesting material. Even so the material was largely intact at the end of the trial. We think it would work well left in situ topped with compost to create new beds on areas of grass.