There was this big anti-real grass pro artificial turf thing in San Antonio years back. A lot of people dashed out and installed this stuff on their property hoping to never use their lawn mower again. They didn't. They had to switch to their vacuum cleaners to keep dust, dirt and other debris away instead. And weed seeds sprouted just like in a real grass lawn. Needless to say there were some upset people. This stuff wasn't cheap to have installed especially when it didn't work. But, to your question. No, weeds will not grow "through" artificial grass