The one I got, same time and place as jan's,
I kept inside for a while. Now it is in my deck
pond, which is fairly shallow, and it seems to
be very happy and growing. It is the only
one I'm purchasing this year as the filter pool
is shaded all the time now and the hornwort
has taken off and can take over the filtering
job - the stuff is sending up seed stalks!

k :-)