hiswife, your irises will certainly appreciate a little TLC, but irises are generally pretty tough critters! The top reasons people start to see diminished bloom on their irises are overcrowding and too much shade. When the clump gets crowded and the rhizomes start crawling all over each other competing for light and nutrients, it's time to divide them. And full sun is necessary for *good* bloom - a minimum of 6 hours of full sun a day.
There are a couple of tricks to getting a longer season from your irises. First, you can move some of your existing irises into microclimates around your yard. If you stick some on the south side of your house, for example, they'll likely bloom before the ones in an average exposure, and if you have a cool spot, they'll bloom later. I have one variety in two places; the ones in the regular garden were all done blooming by the time the ones in a cooler spot started!
Another thing is to expand the types of irises you grow. Getting a range of types can expand your bloom season by weeks and possibly months. Bearded irises come in all sizes, from tiny dwarf plants that bloom on stalks only a couple of inches tall to the tall beardeds that most folks think of when they think of irises, blooming at heights of 27.5" to over 4 feet. The smallest, the minature dwarfs (MDBs, under 8") bloom here in mid-April or so. Then the standard dwarfs (SDBs, 8-16") come in, followed by the intermediate beardeds (IBs, 16-27.5"), and lastly, the border beardeds (BBs, also 16-27.5", but later blooming), miniature tall beardeds (MTBs, same height as the IBs and BBs, but with dainty, smaller flowers, sometimes also called "table irises") and the large tall beardeds (TBs, over 27.5") wrap up the show, generally finishing in mid-June. That's 2 months of irises! AND, within each category, there are early, mid and late-season bloomers.
Not enough? Add some beardless irises: Siberian irises, Louisiana irises, Spuria irises, and/or Japanese irises. The Siberians start up right as the late bearded irises are finishing. Then the Louisianas and spurias start. Then the Japanese. The Japanese bloom here peaks around the beginning of July. Again, early to late blooming varieties within each group. In general, the beardless classes like more water and can be mulched without worry of rot.
But wait! There's more! I've got bearded irises blooming RIGHT NOW! Look for reblooming bearded irises and add some to your garden. They'll start in late summer or early fall, going until frost shuts them down. Note that some rebloomers will only bloom sporadically, or in certain zones. In southern CA, some folks have bearded irises in bloom 12 months a year. In MO, you'll still have a range of good ones to choose from. Here's a link to one year's partial bloom report from the Reblooming Iris Society
to give you some varieties to try. I've had 3 different ones bloom so far this fall, with stalks coming on another 3. Last year, I had over a dozen different ones rebloom. Pretty neat to have irises as Halloween - or even Thanksgiving - decor. And it really messes with the neighbors. "Are those... IRISES?!?!" "Yep!" "What's wrong with them?" "Not a thing."
Yes, I'm an iris junkie. I'm currently growing almost 400 named varieties, plus another 60 or so unknowns/lost tags/passalongs/rescues/seedlings. But there are something like 80,000 varieties registered with the American Iris Society, so I have only just begun... Mwa-ha-ha-ha-haaa!