I brought one of the packs home and hope to grow them into mature shrubs.

I have 'Annabelle' and several Hyd. macs, but have never grown H. involucrata or found any at local nurseries.
Have always heard they were too tender for the landscape in my area, but the PW site states they are hardy to Zone 6 (-10°F). Anyone have experience with these?
TIA

I had H.involucrata for 3 years in my 6b and it experienced severe diebacks every winter. Of course it didn't bloom.
I gave it to a friend in a solid z7 (Long Island, NY) where it produced handfull of blooms this year.
Not familiar with this particular cultivar which might have better hardiness characteristics.
In any event, you have nothing to lose, try and see.

That said, I have not found a single one of the series at any of the local retailers that carry the Proven Winners (PW) line! In fact, I saw no PW plants at all there, throughout the year.
HD is the primary retailer of PW plants in this area and their supplier may not grow the Let's Dance Series or grew tired of having to take back a bunch of dead plants!