All irises will perform well if they are given at least six hours of sunlight. Most irises will not flower if the sunlight drops to less than four hours a day. If you do plant an iris in a partially shaded area of your pond the best sunlight is that of the morning rather than the afternoon sun. This will help evaporate the dew from the leaves preventing the risk of fungus or bacteria. If given too much afternoon sun it can burn up the petals of the lighter irises.
When you first plant a young iris they require less water until they become established, moist soil, little to no water above the soil line. Since an iris is considered a marginal pond plant it is best to plant around the perimeter of your pond or bog area. Most iris will tolerate a range of water depths from moist soil to a few inches of water over their crown once they have become established water plants. Just make sure the crown of the iris always remains moist or in the water. The water garden irises benefit greatly from early spring fertilizer and fertilizing throughout the growing season. You should begin fertilizing irises when the pond temperature reaches 65 degrees and continue to feed them once a month through the growing season, well after they begin to sprout. You can stop fertilizing them about a month before the last frost free date in your area. This will allow the iris to harden off for the winter. If you have no frost in your area stop fertilizing when the plant begins to show signs of going dormant. This would be when the leaves begin to brown and new growth has stopped.
Depending on the iris you have determines the winter care for it. Once the foliage dies back and the water temperatures begin to cool down you can trim the leaves back to about an inch or two above the crown of the plant. You want to make sure they will stay wet throughout the winter. They do best just by leaving them on the shelf of your pond or marginal area of your pond. The main goal is to make sure the iris stays moist throughout the winter. If you do remove the irises from your pond during the winter months where temperatures don’t drop below 25 degrees, make sure you don’t let them dry out. You can place them in a container filled with 1-4 inches of water or enough water to keep their crowns above the water level.
Buy iris,marginal bog plants here.