There are basically 3 'groups' - the beardeds from the very short MTBs to tall TBs, the beardless and the bulbs.

For a wealth of information and links go to the American Iris Society.
http://www.irises.org/

But I would recommend using Chuck Chapman's site for information regarding what will perform in your climate.

I'm in a mild winter zone ~~ sorry I can't be of more help. I do know the bulbs of Dutch iris will not overwinter in zone 4b.

Here is a link that might be useful: http://www.chapmaniris.com/

I've found beardeds the easiest to grow. I know I've just stuck them in the ground and they've done just fine for me. Just a bit of water and that's all I've really done for most of the time. Last year was the first time I fertilized, although the year before, I stuck them in Miracle Grow. Naturally, the soil here is a little on the clay side and alkaline and all my irises take to it just fine.

I've started growing Spurias recently, and I've found them to be easy as well. I've read that they grow fine without division. Beardeds need to be divided every few years, so they're not completely maintenance free. But Spurias might be. I've only had them for a few years, so I'm not really sure on that yet.

Hi Mit,

Chapman iris is a good place to start looking for iris.

The SDB's (Standard Dwarf Bearded iris)seem to be the hardiest, with a large selection to grow in colder zones.
My best tall bearded iris have been...Devenshire Cream, Immortality, rhein nixe, and sweet musette. Of course I am testing many more varieties, but some are not as hardy as others.

If your soil is wet you may want to try siberian iris as well. Bearded iris, don't like to sit in wet soil...especially in spring.

Parkland perennials have siberians, Botanus, Ferncliff and Trails end also have iris.

Happy iris hunting.

Sierra

If your soil is acid and moist, like most of the NE United States, Siberian Iris may be the easiest for you. They grow great here with just about zero care. It rarely gets much below 0 here, so you should check into their hardiness for your zone.

There are ooodles of bearded and siberian iris that will grow in your zone. They are one of my favorite flowers to grow. There are so many to choose from you might first ask yourself what color flowers you would like ;)