But there are some which will have a jolly good try. I have had bindweed growing in the underfloor, and managing to squeeze between the tongue-and-groove floorboard gaps to show itself inside fitted wardrobes. Some also came into the adjacent room through a ventilation grille. Eventually I had to have the floor replaced in first room, and the amount of plant I found growing under the floor was quite surprising. Its origin would have been with plants growing in outdoors, on the other side of the wall, but I had killed all that off some years before.