There are nearly 300 species of iris, many of which are popular in home gardens and landscapes. Proper planting is essential to growing irises successfully, and knowing when to plant the rhizomes is basic to correct planting.
The ideal months for planting irises are July, August and September. When planted in these summer months, the plants develop a healthy root system in time for facing the cold months ahead.
After blooming in spring, irises can be dug and divided, making more plants for next season. Summer is also the optimum time for replanting newly divided rhizomes.
Although planting irises in summer and autumn is preferable, many people do plant them in the spring, when the garden centres stock up on iris rhizomes. However, when planted in spring, irises might not bloom the first year.