Plants that self-seed and choose where they want to go are always far more successful than those that we try to redirect. There's a lot to be said for letting nature re-arrange things for you, as she sees best.
Finding out what colours you get from a packet of mixed seed is always interesting. I grow hollyhocks, and lupins from seed, and have never been disappointed. 
This year I also tried a packet of mixed cosmos - well there were mixed colours on the packet cover, but they've all turned out yellow. 
I don't know why it is that Italians have this thing about tomatoes. Why, in the joke, is it an Italian, and why tomatoes.