magz, if you have whitefly in your greenhouse, try growing french marigolds. I've grown them in mine for the past four years and I see only the occasional fly. My greenhouse this year is crammed with aubergines, tomatoes and chillis, whitefly magnets all, but thre's hardly any flies, certainly not enough to worry about. I think they may work outside too. I've tried growing them among my veg without problems. This year I haven't grown them outside and my brassicas are covered in whitefly.
