Happy 4th of July a bit early, everyone!

I have a question about hypercium, or St. Johns Wort. I googled it to get a bit of information, and just got confused. Some claim it is super invasive, others don't have a problem. Nobody seems to mention it's usefulness as a filler in bouquets. So, I thought I'd go straight to the experts.

I've been selling some flowers to a local florist, and she asked if I could grow hypercium. She uses it quite a bit, and the berries range in color from green to peach to red, etc. Will it grow in zone 4/5, and most importantly, which variety is the best to grow for the berries? I originally thought it was a shrub when I saw the berries in her arrangement, but I guess it's a perennial. Basically, I'm starting from scratch, but the florist is very interested, along with winterberry and a few other shrubs.

So, does anyone have any experience, good or bad, with hypercium? Thanks in advance for your help!

Cathy