Mine do well left in the pond. But we don't freeze hard enough to freeze water. How is the winter where you live? If you pull them out, make sure to keep them wet and in a warmer area. I have done that with both plants and fish. I used a giant Rubbermaid container filled with water and wheeled them into a warmer environment in the garage. It was a lot of work. After I found out they lived just fine without moving, I was relieved.
