Winterizing pond plants

Okay, I tried to research this on the web, where I found a pond supply page
listing water hyacinth and anachris as HARDY WINTER PLANTS--there go that
page's credibility--mine just turn to mush if I leave them in, and I'm in
zone 8!
I have zebra grass, horsetail, pickerel, cattail, dwarf papyrus, canna
lily (can you see I spend WAY too much this spring and want to save some of
my investment) and outside the pond elephant ear, ginger flower and banana
tree (which is probably already dead). I want to keep the bringing of
plants inside to a minimum if possible. I have read things here about
"sinking" plants, which I don't really understand--how do you sink a
plant--put rocks in the pot so it sinks to the bottom of the pond, or what?
Thanks for any help you choose to give!
Kirsten