I bought two smaller cultivars: the red Bunga Baby, and white Angel Wings. The tubers spent a fortnight or so in two buckets of water, waiting for the new rootlets to appear.
[Temporary glamorous home in a bucket.]
Then I potted up Bunga Baby into a very swish container: that garden stalwart, a polystyrene box, filled with garden soil, bought compost, seamungus pellets and a dash of blood and bone. I carefully covered it over with a load of all rocks from the garden do all the soil didn't wash out. Then I put it into the pond (giant black plastic tub) and walked away, whereupon while I wasn't watching, the whole lot flipped over and dumped the contents into the bottom of the pond. Oops. I decided to just leave it there, since it was covered pretty well still, and now I had a spare box again.
Then I repeated the process, with the addition of some Dynamic Lifter I found in the shed, remembered to take some photos this time, and also remembered to keep an eye on the box as it sank into the pond.
[New rootlets, pinky white.]
Fingers crossed for some flowers this year, or at least masses of lovely leaves.