Crinum natans is a very beautiful and graceful bulbous plant with dark-green leaves. Plant so the top 2/3 of the bulb is visible. When the plant grows older (if it is thriving) it sometimes forms small bulbs and sends a flower stem up to the water surface with a beautiful and aromatic lily flower. The plant varies considerably in leaf width and the shape of the leaf margin. It is also suitable for indoor ponds, and is not eaten by herbivorous fish. [TROPICA]
I'm finding this plant to be extremely slow in getting going. Other plants that I planted at the same time have grown to the top of the tank but this one has remained frozen in time doing nothing for 2 months. It's under high light, high co2, plenty of ferts.
You probably buried the bulb, this will slowly kill is. Any bulbed aquatic plant and Banana plant should be only 1/3 in the substrate it it will rot away and you'll only have root but no store nutrients. They morons at most fish store to not know this and often try to sell you very sick and small plants for ridiculously high prices. I had most wither away until a finally got suspicious and looked up the real way to treat these plants. Do NOT bury them in the substrate! It will slowly kill them! I had one die, a few are very small and a couple are still OK. They stared about a foot long and now most are 4-6 inches. ON the other hand I knew to no longer trust them when I got a banana plant and it is thriving since I did not bury it in the substrate.