Easily sprouted by scoring the short end of the seed and leaving in a bowl of water. Nymphaea, or the "true" water lily, has its place in myth and legend, beginning with the ancient Greeks who dedicated the plant to the nymph, a type of water demigoddess.
Zones 4 - 11. This aquatic perennial's tuberous roots colonize the soil at the bottom of earth-bottom ponds, or the soil in containers fully submerged in lined ponds. The stems of the leaves can reach the surface of water that's nearly two feet deep-and then continue upward, above the water, a few inches or even a foot farther.
The roots don't tolerate frost but the tubers and roots are hardy anywhere the water above the soil is deep enough that the pond's surface-ice doesn't freeze all the way down to the soil, and yet is not so deep that their leaves can't reach at least a bit above the water's surface to get the full sun they need to grow and flower: From the frost-free tropics of Zone 11, then, all the way down to the seriously-Wintered Zone 4 of Northern Vermont and Canada.
Few plants, aquatic or terrestrial, have such a world-wide versatility. Growing your lotus in a plastic tub that's submerged in water: Plant the tuber shallowly, on its side, in a dishpan-sized plastic tub of heavy soil. Don't use potting soil, which is so fluffy it would just float away when you submerge the plastic tub. Leave the tuber's growth tip exposed.After two or three of the small starter leaves have sprouted, you can lower the tub (carefully) to its "mature" depth.