How deep is the water? This will be a factor in establishing plants and their survival over winter if you live in colder regions. Some species need a minimum depth of 2 to 3 feet to grow well.
Is your pond permanently installed in the ground or is it a small tub that will be moved inside in the winter? In this case, even tropical plants may be an option.
Will you drain your pond in the winter? If you intend to drain your pond, you should consider plants that can spend the winter in a basement in a dormant state.
How much sunlight does your pond receive?
How large is your pond? If you pond is small, consider dwarf species.
Plants should cover 50 to 70 percent of the water surface. Native plants usually do not need fertilizer. For some exotic water lilies, limited fertilizing once yearly may be required. Check with your nursery on care of plants and how deep to place potted plants. Be aware that overfertilizing may cause unwanted algae blooms, which can rob the water of oxygen.
I*This information was taken from the "Backyard Conservation" kit from the National Association of Conservation Districts. Kits can be ordered from www.nacdnet.org.