And don't tell me they are tired!

I have a few clumps of white irises (flags) which are laying down. They start off upright and the foliage is upright, but as the flower stalks develop they are now more or less horizontal. They do not feel "soggy" They look quite pretty however as they are overhanging a wall  but that wasn't really the idea! The ground is well-drained and sunny south facing and they have been in place for 5 years without doing this before!

Could be that they need dividing to rejuvenate them.

When you go to garden centres, etc, you never see staking, but you also never see large established clumps of irises. The heads are smaller and lighter as the rejuvenated plants are young. when the clump gets larger, the flower heads also get larger, moreso on the new hybrids which put up 3ft+ high flower stalks with massive heads on them. Unless you stake these, they on the ground like a bunch of drunks. For these I find the slim green metal holders with the open top circle is the most discreet for the job and holds up the stalk well.

The ones I prefer (but you can use what you want) are called single plant supports

 http://www.ukgardensupplies.co.uk/acatalog/Plant_Support_Stakes.html

Irises really aren't a pot plant, and 4 in one pot (unless its a biggun) isn't good for them. It's possible you have dwarf irises if 3" is all they've grown so far.

Most newly planted irises can take up to 3 years before they flower, as like trees and such, they need to set some support roots since they prefer to sit on top of soil rather than inside it.

You will also notice in time that the centre of the clump has no growth. This is the time to dig the clump up and divide it.