groundcover is in front of the salvia may night? creeping sedum perhaps?
would grow in your zone. I live in the northeast, and have both of these plants in a sunny location in my garden. In Florida, they may need shade, if they are plants that can grow in your climate.
My May Night Salvia has been in bloom since early spring, same as the Walker's Low Catmint Nepeta. I'll deadhead
I live in East Texas where it's hot and humid in the summer. Hopefully, you can see my Catmint in this photo.
Here's a photo of Silver Mound Artemesis up close. It's a perennial in Texas.
darker blue in the front is is purple salvia or butterfly bush
Want these purple flowers for the side of my house in Florida...
planting them in alternating beds to create a tapestry effect or intermingle them for a more informal look.