All irises will grow well if they receive a full day’s sun and will bloom reliably if given about 6 hours of sun. White or light-coloured irises prefer some shade to protect their delicate petals from drying out too much. Generally irises will not flower if they get less than an average of 4 hours of sunlight a day.
Tolerance of water depth will depend on whether the iris is a true water or bog iris, where water depth is measured from the crown of the plant to the surface of the water. True water irises can flourish in depths from 0 -20cm (0-8”) depending on the cultivar, whereas the bog irises prefer moist soil, i.e. that which retains water but does not have standing water over it. True water irises are equally happy in damp soil as long as they don't dry out but it is best that the rhizome is below water during the hottest part of the year as the rhizomes don't appreciate direct heat unlike some other species of iris. Water irises should always have at least 7.5cm (3") of their leaves above water in order to grow so be careful when cutting back for winter and be mindful of this when first planting in the pond.
Soil or water pH for water irises depend on the variety with most tolerating slightly acid to slightly alkaline and the pseudacorus and Louisiana species tolerating the widest range (5.5 to 9).