going into the 30's for the next few nights, plant question

Hi,
I have some water plans in my little pond, water iris, and water iris. I have a fountian so I know the water won't freeze, it is pretty warm, but at what air temperature do I need to bring the water plants into the house?
Thank you, Kathy

If you have water hyacinthus, I would bring them in just to be safe. I think everything else will be ok. The heat that the pond water collects durning the day should protect the plants.

thank you!