An ABer had very expensive astroturf laid (I'm sure he bought it through John Lewis) with the proper weed-blocking membrane and still the weeds came through.
I had artificial grass in the garden at my previous house. Despite the membrane the weeds still came through. I just went round pulling them out when I saw them.
Ha ha - melted astro turf from using a weed whacker :D
Those weed whackers don't stop the weeds re-growing, regardless of the manufacturers' claims, but it is a lot easier then pulling the dratted things up
The weeds possibly took root within the artificial grass itself.
I had my garden done a couple of years ago and when some weeds came through, I rolled back the edge of the grass to see how they were getting through. The answer is, they weren't getting through - the pesky blighters were taking root within the artificial grass itself. On the plus side, they were dead easy to pull up as the roots had virtually nothing to hold on to.
Dreadful stuff. No wonder all our birds and insects are in decline.
That and people paving over their gardens. Hate it.
My garden is for wildlife. Just going to replace a dead tree with a rowan for berries for birds.