It is best to plant iris in the months of July, August or September. The weather is such that it will give you the best results. It is very important that the roots of iris, when newly planted, be well launched into the soil before the growing season ends. If you live in an area where summers are very hot and have mild winters, it is a better idea to plant iris in the month of September or October. It needs both sun and shade after intervals of a few hours. Iris turns out the best in full sun, even it is provided for just a few hours during the day. Moist soil, great drainage or planting on a slope are some of the requirements.