Hi,

I will have a go at answering your question.

You could try salvia Transylvanica is low growing with blue/purple flowers. There is also salvia Tachiei which is a variation on the salvia Forskohlei, clump forming with blue flowers, the salvia Forskahlei has purple and white flowers.You mentioned the nemorosas/superbas/sylvestris which have a selection off blue flowers.

Just some suggestions for you.

Cheers Annette

What about Salvia 'May Night'? I understand it is one of the more cold hardy salvias.

I enjoy Salvia 'Victoria Blue''s color much more, but I know VB's plant definitely won't survive your winter-doubtful even if you leave the roots in the ground (I live in z7 and my VB came back from its roots the next year). I don't know about VB's self-seeding capabilities-maybe someone can answer this question for you. The only problem I've ever had with VB is that it mildewed BADLY when I underplanted my rose bush with it. I ended up yanking them all out and re-did the whole bed because of this. I did underplant my rose bush again this year with VB in a different, more open design, but the mildew is back-just not as bad this time. I am seriously considering adding 'May Night' to other parts of my garden-right now, I have no experience with it.

Hope this helps.

Here is a link that might be useful: Salvia 'May Night'