“It can be expensive and, I feel, a little awkward to use. Have used it before on a patio and drive - (bought Stone Grey not Mushroom this time) - put it down and used lots of water, 'the wetter the better ' as they say. Unfortunately we didn't strike it and consequently lots of weed seed rooted which I wasn't impressed with. A few years later we scraped it all out, replaced it and firmed it between the slabs - better result this time. Remember to cover with water if you've got some left over and use it in a reasonable time. Bear in mind that it can also 'go off' even if unopened, so check it when you have it delivered and keep your eye on it - better still, use it promptly.”