irises

What type of irises are they? Different types need very different treatment. Some can be kept underwater all year round, some need their rhyzomes planted on the surface so they get baked in the sun. So it very much depends on what you have.

wagger is right, some really like their rhizomes baking in the sun. if they are the tall bearded iris with a fleshy rhizome thats what they need, so leave the top half uncovered. if they are dutch iris with a bulb they need to be planted 2-4 " deep in good soil. siberian types again need planting 1-3" deep. all will benefit from some fertilizer, i usually plant mine with a dusting of fish,blood & bonemeal or equivalent. most prefer sun though i have some dutch in partial shade and they are doing well.
this is the way they are in my garden but i am on chalk so that may be a factor too. what does the rest of you think?

Sorry I should have been more specific about the types of Irises. My Pacific Coast Irises do well in any position in the garden and flower profusely as do the sibericas. The rhizome types I do add some gravel to the soil when I plant them with the rhizomes showing and place these in the sun, but other than the very short pale yellow iris, which flowers well, I have problems with flower production with the rest of the bearded types. My new irises, yet to be planted, are a mix of bearded, Louisiana - which prefer moist soil, so I shall put these near to the pond, and a mix bag of dutch bulbs. Maybe they are lacking in the fertilizer area so I feel I should given them a boost with some FBB. Most of the garden has pretty well drained soil, but I feel that they would prefer some added sand or gravel? Could be the roots are getting too wet?