I'm in VA (zone 7) and have a sunny south-facing slope near the street.
I'd like to find a nice groundcover for it, as it's too steep to mow.
The main problem is that it is an acidic solid clay soil, whereas most
groundcovers want "a well-drained soil" which usually means something
other than clay. Would the steep slope provide adequate drainage? It
always seems dry.

My choices are limited to something that will withstand the summer heat
in that poor soil. On similar slopes I have successfully grown blue rug
juniper and vinca, neither of which my wife likes. I'm pretty sure
cotoneaster would work too, but *I* hate that stuff.

I've been looking at several varieties of sedum, and also the 2006
Perennial plant of the year, Dianthus Firewitch
(http://www.perennialplant.org/ppy/06...%20%20copy.pdf). I have
grown a different clumpier type of dianthus around my mailbox and it
tolerates these conditions fairly well, suffering a bit in a dry, hot
summer but otherwise surviving.

Please let me know if these would spread enough to fill in (preferably
dense enough to crowd out weeds). If there are other groundcovers that
would work, let me know.

Thanks!