My dark knight bluebeards (planted by landscaper 4 years ago) did not come back this year after good 4 years, I need to replace them. I still don't know exactly why. I lost 3 last year and I lost the rest (4) this year. I live in South/East Michigan.

I am looking for bushes with blue flowers that grows 4-6 ft maturity. The spot gets morning sun about 3 hours max and it is against garage wall so well winter-protected. I have clay. Any recommendations are appreciated.

I also look for some other shade bushes of similar size but with flowers in different colors.

Thanks.