2pods wrote:

In or out for the winter ?
Ponds are only 2' - 2.5' feet deep.

As I have no conservatory or greenhouse, if I take them in, can they be
treated as a houseplant with no immersion ?

A pond post! Out, definitely. I doubt an umbrella would survive even a
southern UK winter. Treat as a houseplant, keep in a warm sunny window,
and keep it wet. I used to keep them in the veggie filter I built for my
large (299gallon) aquarium (so completely submersed) but they don't have to
be that wet. They make good houseplants, though, because watering is so
easy :-) Most of my houseplants suffer from inadequate watering, so all I
keep are cactuses and pond plants.
--
derek