Water lilies (Nymphaea) and Lotus (Nelumbo) are jewels of the aquatic world. Symbolic in both the ancient and modern world, they are celebrated for their beauty and immortalized in art and religion. Both are pond blooming plants that emerge from rhizomes and share a rich color palette, but there are some easy ways to tell them apart:
Many of both plants are easy to grow and reward the gardener with fragrant and sumptuous blossoms from June until October.
There are two main divisions of water lilies: hardy and tropical. Hardy ones will survive our New York City winters if they are planted below the freezing line in a water feature, while tropical water lilies need to be stored over the winter or treated as annuals.
In addition to cold hardiness, tropical water lilies differ from hardy water lilies in the following ways:
Plant water lilies in plastic containers or baskets specifically designed for aquatic plants. Line baskets with burlap or landscape fabric so that the soil does not fall through the cracks. (Several sheets of newspaper can be placed on the bottom of the containers for the same purpose.) Always use topsoil that is free from herbicides and pesticides. The containers should be large enough to allow the rhizome to spread. Since rhizomes creep across the surface of the soil, a wider pot is preferred to a deep one.
Planting instructions vary for hardy water lilies and tropical ones. Tropical water lilies should be planted just like perennials. They often come as bare root plants. Place them in the center of the container and let the crown (root-stem junction) of the plant rest just above the surface of the soil. With hardy water lilies, plant the rhizome at a 45-degree angle with the growing tip positioned toward the middle of the pot, resting slightly above the soil level. Cover the soil with gravel or a thin layer of sand.
Each flower on the water lily lasts 3 to 5 days. They open during the day and close at night (unless they are nocturnal). Once the flower is finished, it will slowly sink into the water. Seed pods form and the ripe seeds fall into the soil below. Seed production uses a lot of the plant's energy. To ensure many blooms, cut the dying flowers as they sink below the surface. Follow the stem down as far as it goes and either cut it or snap it with your fingers. Clean off dead or dying leaves in the same manner.
Tropical water lilies can be stored over winter by lifting the plant from the container and storing the rhizome in a plastic bag or container full of damp sand and peat moss at 50 to 55 degrees. Remember to label your rhizomes. Alternatively, you can re-pot the water lily into a smaller container. Trim the roots and cut back the majority of the foliage. Store it in an aquarium tank making sure that the temperature doesn't get above 68-degrees; this control will ensure that the water lily is not actively growing.
Lotus will be hardy if the tuberous rhizomes do not freeze. Plant the containers so that the soil line is below the freezing mark in your pool. This can be from 6 to 18 inches deep depending on the size of your water feature. Lotuses, like water lilies, prefer six or more hours of sunlight. They die back at the end of the year. Cut them down to a few inches above the rhizome. Be patient with them in the spring as they are late to emerge. They prefer warm weather and will start to grow once the water temperature has risen above 70 degrees. The first new leaves of the lotus float on the surface of the water, while older ones are raised in the air.
The American Horticultural Society Complete Guide to Water Gardening by 
Encyclopedia of Water Garden Plants by 
The Water Garden Encyclopedia by 
