????

Was the picture taken earlier in the year? It reminds me of Persicaria polymorpha (Giant Fleeceflower) but I'm also in Ontario and the ones here are more advanced in their flowering than that right now.

I just took it today!!

It could be it, though as noted, mine starts blooming at the end of June, and continues into fall, with the inflorescences aging to a cream colour and eventually to reddish brown.
There are other Persicaria species that are similar and later blooming, e.g. Persicaria polystachya, one I'm not familar with. Another possibility, perhaps (again one I'm not familiar with), might be Persicaria campanulata? A close-up of the flowers might be helpful, and also some idea of how tall this plant is. I've had mine for so long that I don't remember what it looked like as a young plant, height-wise or with respect to bloom time!

Edit: Okay, I see that you posted a flower close-up. It's definitely not Persicaria campanulata then.

Perhaps the history of the plant might help (I notice the Physostegia next to it is still blooming, I thought they had finished here but I will check). Was it purchased this year in a pot, or was it divided from someone's clump, maybe it had been cut back earlier for some reason which could delay flowering? Or has it been growing in that spot for more than a season undisturbed? The established Persicaria polymorpha here is at the reddish transitioning to brown stage, but some that I had to move are still flowering white. The latter are still more advanced than the picture above though.

Is your 5a zone on the Canadian zone system or USDA?

I took this picture at my workplace yesterday showing Persicaria polymorpha for comparison. The plant on the right has been undisturbed for two or three years. There were originally three but I had to move the other two for some projected construction work. A little piece got left behind and as a consequence is behind in growth and flowering, see the left one which is shorter with the flowers later and still white. The picture is a bit dull as it was taken around 6.30 a.m. just around dawn.



I also have the picture in higher resolution, and also others closer-up if that would help. I thought I read somewhere that we should keep images below 500k. Not sure if I'm remembering that right, but just to be on the safe side I resized.....

Sounds like a logical explanation for the late bloom and short stature.

It is definitely a Persicaria polymorpha, because I found the name tag!!
Thank you everyone's participation!!

BTW, sooby, I live in central Ontario, I bought it in July, so it has been in my garden just about 2 months. It has grown a lot bigger then when I first got it. Hopefully it will be big like your right one next year.

I'm pretty sure they were originally planted in 2012 so it doesn't take long to get big, and it does get pretty big. It's a super plant though, and one doesn't see it planted very often. (I'm Eastern Ontario).