Calendula

I'm growing calendula Lemon Daisy (I think), they're yellow (DUH naturally)  and dwarf. They are so easy, but how do you stop them getting powdery mildew and starting to look really tatty.  BTW I will prob have seeds of this for the seed swap if anyone wa ts them.

Grow lots of other plants around them and you won't notice the leaves!!
I've been collecting the seeds as they dry and scattering them elsewhere in the garden. You can never have too many calendulas, with or without manky leaves!!