Nymphaea

So I am investigating the options of which smaller, hardy species of Nymphaea to put in my barrel.

Am I correct in saying that it will go dormant over the winter?
Should I buy it now, or wait until next spring?

 

I think you need the smallest possible for a barrel.
They tend to be the most expensive.

You could buy now, hopefully get an end of season bargain.
Yes it will just die back slowly during the autumn, the first frost will kill all the leaves.

 

Pete,
Will it come up again next spring when the weather warms up?
Or will it need special treatment? A container in a greenhouse? Or indoors?

 

It should overwinter in your barrel, assuming that the barrel cannot freeze solid. It should then come back each year, getting slightly bigger and stronger each year. HTH