Water iris adds color to your backyard pond or container water garden. These flowers bloom in late spring and early summer, producing the large, drooping blossoms that set the iris apart from other flowers. Potting the iris is preferable to planting directly in pond bottoms, as you can easily relocate the plants if desired. Potted water iris also are simpler to divide, since the entire pot can be removed and the roots easily accessed. But you should know that potting water plants differs from potting regular garden plants.
Fill a 1-gallon pond basket with a clay-based potting soil, leaving a 2-inch space between the top of the soil and the basket rim. Pond baskets have small holes in the side that allow water to pass through to the soil. They are available from garden centers and pond supply stores.
Sow the iris rhizome so the top of the root is just beneath the soil surface. Plant with the buds facing upward, as the leaves grow from these buds.
Cover the surface of the soil with a ½-inch layer of pebbles. Pebbles prevent the soil from floating out of the basket and protect the iris roots from scavenging pond fish, if applicable in your water feature.
Set the pot inside the pond so the rim of the pot is 3 to 4 inches beneath the water surface. Place bricks under the pot to elevate it to the proper depth if necessary.