A Spring ritual is putting aquatic plants in clay flowerpots and placing them in my small outdoor pond.
A few years ago this killed some of my fish.
I start with flowerpots plus some clean sand and gravel.
Gravel goes on the bottom.
Then the plant, maybe a little soil, then sand on top.
As I mentioned, a few years ago there was a problem. I had fancy goldfish, platies and swordtails in the pond. Everything seemed fine but after a week the goldfish were dying and the small fish had quit eating and were sitting at the bottom.
I captured the remaining fish, then completely cleaned the pond. I still had no idea what had happened.
It was a year later that the president of the local fish club (Mr. LVH) said something about pesticides in used flowerpots. It became clear as a bell.
I had bought some used flowerpots at a garage sale. My first use of them was in the pond. Things were fine for a week but then the poison began leaching out.
Another week went by and I had dead fish. The ones that were brought inside were thin and disfigured but, if they could be induced to eat, recovered quickly.
So if you buy used clay flowerpots soak them for several days in a bucket of water. Pour out the water and do it at least 3 times over a week.
Also in Springtime I put Water Lettuce outdoors that has been growing in an aquarium.
First, I put the plants in a plastic container and tuck it in a shady spot to avoid sunburn.
If I move it into sunshine too soon it looks like this.
Water Lettuce can recover and eventually gets accustomed to bright sun, but I think it does best in partial shade.
Partway through summer I have to remove handfuls of Water Lettuce from the pond.
I also have flowerpots in several of my aquariums.
Amazon Swords do best growing in soil.
The only problem growing aquatic plants in pots is that the plants grow too fast. The tank becomes a jungle. Not a bad problem to have.