How to find a plants flower size

You can look this info up for any patented variety. There are two ways to do it, sometimes one is simpler than the other for reasons I don’t understand.
USPTO search: https://assignment.uspto.gov/patent/index.html#/patent/search – for this one, select “patent number” for the “look up by” menu and enter PPxxxxx – no spaces or commas.
Google patent search: https://patents.google.com/ – for this one, it’s best to search by genus and cultivar in single quotes (if the cultivar is a common or real name) or just the cultivar, with or without single quotes (if it’s a more unusual name/word). You have to try different things, and I usually find that the Google results are better spaced and hence easier to read.