Weedkiller that won't harm neighbourhood cats - does it exist?

Forwandert

Are they actually growing through the membrane or on top of the gravel and rooting down.

I have gravel around my border with membrane underneath and provided I don't leave them too long I can just rake them out without any issues, they only get down about am inch or so in the gravel if not left too long. I just do it every time I mow the lawn and takes a couple of minutes.  There was a couple that where growing through the year after I put the membrane and gravel down and did have to kill them off but they haven't been back growing in that area since. 

Rosa_Damascena

531063 said:

Rock salt                                                                                        .

So they die by dehydration rather than poisoning?

SaintJudy

Forwandert said:

Are they actually growing through the membrane or on top of the gravel and rooting down.

I have gravel around my border with membrane underneath and provided I don't leave them too long I can just rake them out without any issues, they only get down about am inch or so in the gravel if not left too long. I just do it every time I mow the lawn and takes a couple of minutes.  There was a couple that where growing through the year after I put the membrane and gravel down and did have to kill them off but they haven't been back growing in that area since. 

They're doing both. I have a few that just seem to grow within the gravel and I've been raking those up, but there must definitely be punctures in the membrane and some grow straight through. I wasn't living here when the membrane was put down, it must be 10 years old at least now.