Davy wrote:

OK so gravel it is rather than earth. But will I need to add some soil to
the gravel at first to get the plants growing or can water plants grow in
clean gravel?

_Many_ (but not all) water plants can grow without soil. I tie my lilies to
a rock, and drop them in - they don't have gravel or soil. Cattails and
irises do fine without soil. With plants I'm not sure about, I'll try some
bare-root and some in soil and see what does better.
--
derek