The Right Soil
When creating a water lily garden it is always best to start with the proper soil. Hardy and Tropical lilies prefer good, firm, enriched garden loam. Beginning with a poor soil, and trying to build it up with fertilizers, is not effective for these plants. Weak or poor soil, even with fertilizers, will cause the plant to go to foliage.
Do not use Swamp Muck either, this may appear rich, but it will not work. The muck has very little nutrients in it. Muck is mostly a result of plant decomposition, which as it decomposed, releases harmful gases, creating an unhealthy environment for your fish and plants.
River Mud is also unacceptable. Leaf mold will also foul up the pool water as it decomposes, eve though there is some plant food in it. Heavy clays are good for water lilies because they contain potash. Clays should only be used when mixed with a lighter soil, or sand. This way the roots of the lilies can penetrate the solid clay and absorb food.
Repotting and Danger Signs:
Tropical water lilies are usually thought of by gardeners as annuals. This means that the gardeners let their plants die in the winter and reorder plants in the spring. Some may take their plants indoors and propagate them during the winter months. Tropical lilies must be set out new each year, in new water with a fresh supply of soil and fertilizer.
Hardy lilies can be left go during the winter, but remember to repot occasionally. Sometimes the food source may need to be replenished as well, even after one season, especially if it is only planted in a cubic foot of soil and fertilizer. Hardy Lilies that are planted in more spacious holding containers will probably be good for two to three seasons. Make sure to lift Hardies up from the water every three to four years. Make sure you trim Tropical lilies down a bit, and trim some of the growing points from the root stocks.