It sounds like the sunflowers and nasturtiums are decoys. I've heard that clover, mint, and pennyroyal discourage aphids by their smell. My grandmother swore by onions and the onion flowers are actually interesting in a flower garden. I have garlic planted with mine but its too early to tell if it works. They say catnip works but I'd be careful where I plant it. In the right place it would lure cats away from the roses, but in the wrong place it would draw them in. My catnip is in a corner with spearmint in a container in the other corner and garlic all in between.

I don't know if these will actually help, but I figured it couldn't hurt and its an excuse to buy more plants. :^)

Lori