Where are you growing them? In nature it is found in sand or water loged soil of fresh water systems, water usually only about 1-3 inches deep. They are also found in deep shade under the forest canopy, so too much light might not be good.
I have never grown these, only observed them in the wild.

I tried them indoor and now placed them in the fridge for couple of weeks most likely they will go outside and see what happens. I placed the pot into bigger one with some water so soil is pretty moist.