Northumberland,
United Kingdom 
I'm tempted to buy a dwarf water lily (nymphaea). The catalogue says that they are winter hardy, but I'm assuming that I would have to protect them in Northumberland where we get quite severe frosts. Has anyone got any experience of them?
17 Mar, 2012
Answers
we have one, the pond got frozen on the surface for a short time, lilly has a flower bud on it already
18 Mar, 2012
I haven't got a pond - the catalogue i saw them in is showing them in 25cm plastic pots. I've seen a tip where people put a tennis ball in the fish pond to stop it freezing. My dog has lots of old tennis balls I could use LOL :-D
19 Mar, 2012
Assuming you will keep it submerged in a pond the only protection required is to stop the water its in becoming frozen solid .
18 Mar, 2012