In very hot areas though, some shade in the afternoon will help keep flower colors from fading in the heat. Iris should be planted in an area with good air circulation to help prevent disease problems. Most iris need very well-drained soil. Japanese and Louisiana iris will grow in wet soil. If your soil is not ideal you can amend it with organic matter and build raised beds for better drainage.
Manure can encourage iris soft rot.
Bearded iris prefer slightly alkaline soil. Many of the beardless iris like a more acid soil. It is a good idea to test your soil and amend the soil before planting a new iris bed. Fertilize a new iris bed when preparing the soil before planting with a complete fertilizer low in nitrogen and high in phosphorus and potassium. Follow soil test recommendations for best results.