Iris blossoms grow from a rhizome, or underground stem, and leaf fan configuration that protrudes slightly above the soil. In order to increase the flowers' longevity as a cut arrangement, remove an iris flower stalk from its plant in early morning. The outdoor temperature is usually cool then, and the iris has had all night to absorb as much moisture from soil as possible. As the sun rises, an iris loses water to evaporation and transpiration processes. Any heat stress significantly reduces the flowers' longevity as cut blossoms. If you cannot cut the flowers in morning, your next best option is waiting until evening.
Do not choose an iris stalk that is in full bloom for your arrangement. Blossoms remain open for about only three days. So a full-bloom stalk is reaching the end of its aesthetic appeal. Instead, look for a flower stem that has numerous closed blossoms with only one that is opening. Using sharp gardening shears, remove the stalk from the plant, and create a 45-degree angle cut on the removed stalk. The stalk's vascular system is wide open to water absorption with that cutting strategy, making your iris flowers last up to 10 days in a cut flower arrangement.
When you cut an iris flower stalk from a rhizome, you eliminate potential rot and disease from entering the partially exposed root system. As flowers fade naturally, molds grow on the blossoms and eventually fall to the ground, where the rhizome may be infected. As a result, the iris succumbs to disease and fails to flower in the future. You also impede seed formation by using iris blooms in cut flower arrangements. Without seeds to create, an iris plant redirects energy into rhizome storage, where future blossoms eventually form from the extra nutrients.
Although you can remove iris flower stalks freely, do not damage or remove any foliage. Fading iris leaves still photosynthesize, storing energy for future blossoms. Cut the foliage away only if it is completely yellow and papery to the touch. Any green pigment remaining on the leaves is photosynthesizing. Future flowers need ample rhizome nutrient supplies for their prolific growth.