I don't have that particular Hosta but I have had problems in the past guessing the size. When I was putting all my Hostas in the data base I looked all of them up on 4 different websites and would get 4 different answers. I found out with the daylilies that the information they give when they register them is sometimes a guess. Maryott's went and evaluated all his daylilies and lots were registered wrong. I give more weight to the nurseries who grow them year after year because I think they have more experience with the real facts. I read things on the nursery websites that the Registrant probably never knew when they rushed the plant to registration. Most of the nurseries I checked with said 12x24 except Hostas Direct said 13xno, for some reason they declined to give a width.
Countryboys, Hallson, New Hampshire Hosta, Hostas Direct