The white Siberian iris is not as common as the bearded iris, but it is far easier to grow. The plant features grass-like foliage with delicate white iris flowers that have no beards. Each fall the foliage of the plant turns a rusty red in appearance. The Siberian iris normally blooms in the late spring to early summer. Because of their delicate diminutive size, the Siberian iris is ideal for gracing the front of a perennial border.
The white Siberian iris should be planted in a spot that offers at least six hours of sun per day if planted in the northern area of the United States. Plants that are planted in the deep south should have partial or dappled shade to protect them from the ongoing heat.
Plant the white Siberian iris in soil that is rich in humus. They prefer to be planted in soil that is slightly acidic with a pH of 6.0 to 7.0. The Siberian iris always appreciates an addition of peat moss to the soil at the time of planting. Mixing a ratio of 50 percent peat moss with 50 percent garden soil is ideal.
The white Siberian iris has intense moisture needs. The plants can even be planted successfully in water-logged areas or damp areas, according to the University of Minnesota Extension. During the growing season the Siberian iris should have a minimum of 1 inch of water per week. The Society for Siberian Irises states that the plants can tolerate drought conditions. Three to four inches of mulch such as peat moss, bark chips, sawdust or recycled plastic mulch should be placed around the plants to help water retention and keep weed growth at bay.
Care During Flowering
You don't have to remove spent blossoms to encourage reblooming. The stalks can be left on the plants during the blooming season. Once the plant is completely done flowering, the dead-heads can be snipped away with a pair of pruning shears.
Care In The Fall
The autumn foliage display of the white Siberian iris is quite pleasing. After the first hard frost the foliage will turn a rusty red in appearance. Do not remove the foliage at this time. When the plant has completely withered and died, the foliage can be cut back at ground level in preparation for winter and spring.
Apply fertilizer in the early spring when the foliage first appears, during flowering and in the height of summer. Apply a basic 10-10-10 plant fertilizer and water thoroughly for best results.
Every three to four years the white Siberian iris will need to have its tuberous roots/rhizomes divided to encourage new growth and for transplant purposes. Division and transplant can take place in the early spring or late fall. Divide and transplant in early spring in cold climates.