WEED MEMBRANE UNDER NEW TURF?

JAYJARDIN · October 2023

We are having the garden landscaped and the chap wants to put old weed bearing soil under weed membrane, then add 100mm of top soil and then lay new turf. To my mind this is not correct and the weed membrane will stop the grass from rooting properly and impede worms. Am I right and the weed membrane should be avoided ? If we lay the turf before the end of October, being in North Devon will it survive the Winter or should we put up with a mud bath of soil over the Winter and lay the turf in the Spring ? We don't want to waste our money and need to have it laid twice.

Fairygirl · October 2023

If there's enough soil on top if it, it won't prevent the grass growing, or the turf rooting in, but it seems an odd thing to do. Have you asked him the reason?
I don't know about turfing just now in your area, but as it seems to be very mild these days in so many areas, it would probably be ok for getting it established quite well without it freezing first and not getting bedded in nicely. I wouldn't want to risk it here.

nutcutlet · October 2023

What sort of weeds are in there. There are always annual weeds and easy germinators and new topsoil will include these. It's not something I'd do

Dovefromabove · October 2023

I agree @nutcutlet … if any perennial weeds have been removed as they should have been there’s little point in a weed membrane under turf.

Fairygirl · October 2023

I think I misunderstood - I missed the fact about the underlying soil being weedy. I assume the chap thinks the membrane will prevent any of those coming back then.
Properly prepped, ie the weeds removed, then I agree there's no need for a membrane to prevent those returning.
If he's done the prep, I think I'd be a bit concerned about how thorough it is too.

Busy-Lizzie · October 2023

I've never heard of such a thing! The area should be dug or rotavated, weeds removed, then flattened.

There should be time to turf it now. That will give it a chance to settle in and root down before winter and it will be better able to survive drought next year, should there be any.

Regular mowing, once it's growing well, will deal with annual weeds and perennial weeds, such as dandelions, can be dug out.

Plantminded · October 2023

Do you know what type of weeds they are? To want to lay a membrane on top of them suggests a lazy way to deal with something persistent like horsetail, ground elder or similar. They need to be eradicated first before spending time and money on turfing. Once this has been done, I'd lay the turf in the spring if there is no sign of the weeds returning.

MrMow · October 2023

I have to agree with most of the above. If the ground is prepared well you should not need a membrane.

Now here’s why.

Many decades ago the shortcut people and a fad a time would lay a membrane as it saved putting in a sand layer or what was known as a blinding layer.

So fitting a membrane was cheap and fairly easy.

But the down side they also cut back on a suitable root zone ( the soil). So if the root zone had lots of fines or silts in it, this would slowly migrate down and slowly block the membrane and after several years you were left with a waterlogged surface. And any warranties you had were long out of date and you were left with the repair bill.

JennyJ · October 2023

I agree it's the wrong approach. Get the weed roots out as much as possible. Any that regrow through the new lawn could be spot-treated with a lawn weedkiller, or just keep slicing/mowing them off. It'll probably be next spring before they're growing strongly enough for a systemic weedkiller to work.

If you suspect your chap might be taking shortcuts, make sure at least that he firms the ground properly before laying the turf (the "gardener's shuffle" - treading all over it with the heels, little tiny steps so that it all gets an equal amount of treading, then rake over lightly to level the surface) Otherwise you could end up with a very uneven lawn where the soil settles later. Have a look at this video https://www.youtube.com/watch?v=J2Tv-ML36r0 The shuffle starts just before 2 minutes in. Rolling with a roller or driving over it with a mini digger or some such thing doesn't do the job.

Edit: probably best to make sure the turf isn't the kind with plastic mesh in it (if that's still a thing - we had some discussions about it on here, a few years ago I think).

JAYJARDIN · October 2023

Sorry for no responses after such a fantastic amount of help yesterday but our Wifi was down ! Thanks so much everyone, I thought the weed membrane was a big NO but wanted it confirmed by those who know. I will make sure he does the gardeners shuffle before laying the turf. he has put weed membrane under his at home and has come clean and said that to be honest it's starting to go bald at the edges now. There's no ground elder or horsetail here, just your normal lawn weeds, dandelions etc which i don't mind as the bees love them and clover a lot.

Thanks again, really appreciate so much info from everyone.

thevictorian · October 2023

Normal lawn weeds will still happily grow with the membrane, the existing ones just won't come back up through it. Most pest weeds don't need much soil depth.

WEED MEMBRANE UNDER NEW TURF?

Posts