This spring, I tried 3 different ways, after checking all the lily pots and dividing the new
rhizomes.
Most of them I potted with half clay and stone pieces on top. Till now koi stays away. They start blooming.
Some of them I put into big buckets with and without soil and keep them outside of the pond. Both have reasonable amount of leaves but no blooming yet.
And the last 3 rhizomes I just hang with strings into the pond. Yet, they have very small and short leaves, not yet on the water surface. But these 3 were young rhizomes and it is not fair to compare with others. Tomorrow have to put them back into the dirt and hang some other mature rhizomes, I believe, to see the result more fairly.