If you're thinking of planting without a container, say in the waterfalls or
in a bog, please consider the mature size of the plant. When it comes to
Yellow Flag Iris, I am dense enough to have to learn this lesson twice!
First time I planted that small little slip of a plant I put it into the bog
(what I refer to as a bog, not a 'real' bog). After growing for 2-3 seasons
that dang thing was 4' wide by 5' tall and fused to the bottom of the bog.
I got rid of all but one little piece that I put into a container. On a
whim, I tucked a small little slip of a plant into the top of the
waterfalls. Mistake. It was so large that it was busting out the side
walls of the waterfalls. I had to remove the liner to get that thing out.
It was too dense to 'cut' any pieces out, but after 2 hours I finally
dragged it's butt out of the pond. Tomorrow it's going to the compost pile.
--
Wendy* in N. California,

"Acquiring a dog may be the only opportunity a human ever has to choose a
relative." Mordecai Siegal