The most typical reason an iris fails to bloom is lack of sunlight. Irises need at least six hours of direct sun per day. Other causes include over- or under-watering, borer infestations or overcrowding in the iris bed.Continue Reading
As perennials, irises need to establish themselves in the soil before flowering can begin. This can mean a wait of several months before a gardener sees flowers on her iris plants. Once established, irises are hardy plants that are drought tolerant and do well with less watering.
Overcrowded irises cease blooming as well. About every three years, they should be thinned out and larger rhizomes replanted to allow for sufficient air and nutrient circulation. If any rhizomes show signs of borer holes, they should be discarded and only healthy ones replanted.Learn more about Gardening & Landscapes