There are quite varying sizes to different cattails, some can be 8',
some just 2' ....all of them prefer to be fully submerged with their
roots in water, just for proportions sake I'd say don't put them
deeper than half their usual growing height, or the roots and shoots
are likely to go all straggly in water too deep, with wind tossing
them about as they travel out of the pot.

About a quarter of their usual height to the top of their pot would be
a reasonable compromise, too deep and the lanky straying rhisomes will
soon be be wobbling at odd angles in any breeze

It is hard to drown cat tails

Regards, andy
http://www.members.aol.com/abdavisnc/swglist.html

(RED1102) wrote in message ...
Does anyone know how deep you should put cattails in your pond?