Ah, but Adam, I have them in several different spots, just to see how they do, plus to extend my bloom times.  I actually have a few MDB's in my front shade garden, where it does get early morning sun for a few hours.  They all bloom.  Sleepy Time is extra lovely in the shade.  I guess because of that, I have a self sown iris in amongst the hostas, just across the path.  It gets less sun, but looks like it might bloom this year.  :)
 
A few years ago, the powers that be updated the climatic zones.  My area went from 3 down to 2b, which I refuse to be.  :O  However, I think a 3 here is equivalent to your 4.
 
El, near Winnipeg, Manitoba, Canada Z3