According to the Missouri Botanical Garden (see link), Rudbeckia is hardy to Zone 7. Echinacea purpurea is hardy to Zone 8. That would suggest Zone 9 is too hot for both.

Here is a link that might be useful: Black-eyed Susan

Hi
I've grown both in S. florida usually they die out during the hottest most humid part of the year . Seems to depend on night temps and amount of rainfall?? gary

Oh wow... good to know. Thank you gardenweed & gary.

Depends on which rudbekia you are growing. Rudbeckia auriculata is rated to zone 10B Offered by Plant Delights.
MBWD