Physostegia Virginiana would be my guess. Leaves don't match lobelia, penstemon (although close), delphinium, salvia, but they are almost a dead ringer for p. virginiana.

Here is a link that might be useful: p. virginiana

Thanks, Aurora. Really appreciate the fast response!!

I also checked that image of physostegia earlier and what made me think it wasn't, was the top where it hasn't flowered yet. Or could that be where the flowers were, and they've now finished?

Hmm, now you have me thinking. Let me look around and see what else I can dig up!

I think it's Nepeta/Catmint.

It sure does look like some catmint at the back. but not the big tall one in the front... lol still a toss up between lobelia and obedient? Leaves are wrong for penstemon i think.

maybe some kind of Nepeta nervosa

Nepeta subsessilis, possibly 'Grand View'.