Not sure where you are but here in Zone 2, PLSCs are only hardy to the snow line. I have one in my front yard which is a tiny (but reliable) shrub much like you would expect a dwarf spirea to look. Therefore it never gets a chance to flower much. Apparently they do produce small black cherries, but not a lot of them, and they would probably be eaten by berry-eating birds such as robins.

Rocky - we've had a PLSC for about five years - blooms every year but has never produced any fruit. Not sure if that is typical or whether it should produce fruit...:-)

I had them flower many times but never seen a single cherry, perhaps a pollinator is needed.
Have dug them out, was tired of pruning back every year.

Konrad