But you’re OK with potted plants, obviously.
If I noticed, I’d probably think “Oh, flowers are pretty.” The end.
I wouldn’t really think about the person carrying them at all.
This.
I would think, ‘flowers, how nice. I wish I had flowers. Maybe I should buy some flowers. Nah, it’s a waste of money.’
I doubt I would even see the man attached to them.
+About what, six now? 
I do like to get flowers and have them in the house - they’re flowers, they’re pretty. As for the guy holding a bunch - I don’t think they would make him less or more attractive to me. I think they would signal his unavailability, but since I’m married myself, it doesn’t really matter.
I’d be inclined to give him the benefit of the doubt that they weren’t doghouse flowers and think kindly towards him, but his attractiveness would depends on a whole lot more than the flowers.
I once was in line behind a younger man at Trader Joe’s who was buying a rosemary plant for his girlfriend. He turned to me and asked my opinion on his choice. I told him I thought it was very romantic, as rosemary is for remembrance, and practical, since it was a potted plant that could be used in cooking (together!) and would last a long time (symbol of his non-flightiness and seriousness) and it was a lovely plant in shape and size. He fretted that she wouldn’t appreciate all those reasons (which he had already thought about) and think it less impressive than cut flowers. I told him if she didn’t appreciate the gift, she was not the girl for him. He nodded, agreeing, but I could see he was still worried. I wish I had given him my number and asked him to call and let me know how it worked out…and since he was very gorgeous, if she dumped him I’d love the plant! But ah, he was 20 years younger, at least, and even being gorgeous couldn’t overcome that!