Heavy clay works best for lilies, sometimes shoving fertilizer pellets into it. Lotus plants are very similar. These plants tend to pull most of their nutrients out of the water, which helps with clarity. They prefer their roots to be anaerobic with no water flow, so clay in pots with not drainage makes them happy.
I use larger plastic pots that are low, maybe 8” tops, no drainage. Also long window planter boxes work if you want a strip or two of Louisiana irises.
The big problem is when lilies get large, they like to float as the roots and stems are full of gasses. I’ve had to weigh things down with ropes strapped between concrete blocks and straddled over the top of the lilies to sink them.
There are a ton of options for water gardens. It is a fun hobby except for the cleaning out the fall leaves part.
Oh, and small fish to control skeeters.
