Can someone in or near my zone (z6a, north of Boston) tell me how tall and wide I can expect my salvia to grow? I've been googling the ones I'm getting but the sizes fluctate by many inches from website to website. Argh :)

I will have Blue Hill (3 plants), Caradonna, and East Friesland. Bluestone seems to think they are all 24" tall and should be planted 16" apart. Is that right? They look a lot bigger than that in pictures!

They're going in with my David Austin roses so I'd like to TRY to get them right the first time as I don't want to be moving them around if I don't have to!

Thanks :)