Hostas will most likely rot. They like moist conditions but not soggy.

I have quite a few hostas floating in my pond in "floating islands" that I made using foam pipe insulation around the rim of hanging basket (wider curved rim) I also have hostas planted in the rocks in my stream - they have done well now for two years - flowering right now. If I can figure out how to post a picture, I will. If someone could post instructions, I would really like to learn how to add pictures.
Audrey

I have hostas planted in logs that are wired right at the water-line to hide the black rubber edge of the pond. Also in pots that are set in water at water level. They are doing great, and have come back year after year. I wish I could tell you what kind they are... Just know they are smaller varigated variety.

Audrey,If you write HOW TO POST PICTURES in the search box (upper right hand) you will get many different ways to post.I liked reading all the different ways because some were more to my liking.
Good Luck!

I've grown hosta in water and they grow like weeds and love it, keep the crowns above water and don't worry.

Here is a photo of hosta planted bare root in my stream.

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