Water irises are not actually grown in water, but alongside it. They are more like bog plants than water plants because, though they can handle a few inches of water, they prefer wet soil to being submerged. Water irises are a lovely addition to the side of any pond or drainage ditch. They come in many colors and varieties, some hardy down to zone 4. Planting water irises is simple because they grow easily.
Choose a variety of water iris that will survive in your climate. If you live in a cold area, choose a variety that is hardy enough for your winters.
Choose a spot for your water irises. All water irises need constantly moist soil and full to partial sun.
Fill a pot that is flat and wider than it is tall with slightly acidic clay soil or aquatic potting soil. Do not use regular potting soil, because it is too light and will float away.
Dig a hole 2 to 3 inches deep, and place one water iris rhizome in the hole. Cover the rhizome so it is just showing above the soil.
Place pebbles over the top of the soil so it will not float away with the water.
Submerge the pot just to the point where the water covers the pot's edges and can flow in and out. Your water iris sprouts should be just above the water level.