Will a bulk-ballast bag work as anti-weed membrane?

[Bert Coules]

The subject line says it all, really. Rather than buying custom-made permeable anti-weed/anti good-soil-washing-away membrane in a new raised bed, can I use material cut from those cubic-metre bulk-delivery bags?

Thanks.

[Tim Lamb]

In message , Bert Coules writes

I've used them under pea gravel. (one way of getting rid of agricultural fertiliser bags:-) They are about as good as the cheaper brands of black mulch.

If you are planting up your new raised bed, where are the plant roots to go?

[Bert Coules]

Into the layer of topsoil which will lie above the membrane. They'll be ground-cover plants which will grow quite happily in a shallow bed. Thanks for the info about the bags.

[Chris Hogg]

If you've got soil above the membrane sufficient to grow ground-cover plants, it will be sufficient to grow weeds. If you're hoping that the ground-cover plants will smother and choke out the weeds, then you don't need a membrane. Usually you have the membrane on top of the soil and cut X-shaped holes through which to plant your plants. Then you put a mulch of something like chipped bark over the membrane to hide it. That mulch will get moved around by weather, birds etc and look really tatty if its a white bulk bag. Get proper black membrane; much less obvious when it becomes exposed (and it always does).

[Bert Coules]

Chris,

Thanks for all that but in fact the primary reason for the membrane is to stop the top soil leeching away through the hardcore-topped-with-sand which will constitute the bulk filling of the raised bed. I referred to "anti-weed membrane" merely as a handy label.

[Chris Hogg]

In which case, IMO cut up bulk bags should be ideal.

[Bert Coules]

Chris, thanks for that: I thought they might do, but I wasn't at all certain.

[Martin Brown]

Yes, but only if you want to cover a rather small area.

The rolls of the proper membrane are wider and the edges are always weak spots where tough persistent weeds like thistles can lift it.

What are you going to put on top to hold it down?

Wood chips or gravel? (the latter works much better long term).

[Bert Coules]

Martin, your post overlapped with my reply to Chris. The membrane is going over hardcore topped with sand, and there will be a layer of soil on top of it. It's more to stop the soil leeching away downwards than to prevent weeds growing up.

[Capitol]

Probably. It won't work anyway even if you buy the nominally correct membrane. The damn weeds will always grow on top of the membrane even if theory says not! As well as the ones which grow through.