It would be best to wait until after the first frost and then cut the stalks off at about ground level. If you're doing it right now, it won't make much difference where you cut them. The stalks won't be of any further use to the plant this year whether long or short.

i planted some pond plants this past spring. i am looking for info on fall cutback and how to split the plants (cutting stalks or whatever) to get more plants for next year. any info is appreciated. i have some water iris', hibiscus, canna, and ruellia. i am new to this. thanks eric

Sondra,

The trick is to be sure there is an eye or growing end. I trim mine to about 8 inches when shipping, cutting them clean, and dusting with a fungicide all over.

Eric,
on the canna, you don't have to divide to get new ones, they should be multiplying on their own, can't see your zone, so I don't know if you need to bring them in for the winter, but in order to trim them you just trim them back, like nicolo said almost or to the ground, don't know on the other stuff!
(sorry for hijacking your thread sondra)

Thanks everyone....now if the rain would quit so I can dig some up!! LOL Poor Jen has been waiting on me, but the weather has been aweful...

ps. Micke..no problem..you are a great help to me and other's...:))

i was under the impression that when i got them i could perminitly plant them in my pond and not have to worry about winter. i live in chicago. they are planted in pots that i can not remove from the pond.
eric