Only those with rhizomes.

I'm new to all this I thought they all had rhizomes.I have baby blue iris..hope this helps ..thank you :)

Most temperate Irises are rhizomatous but those in more tropical climates are bulb producing. Basically for most of the Irises in the UK they are rhizomatous unless they specifically mentioned as bulbs. Personally I would split rhizomatous irises (in March like I do with Crocosmia) earlier in the year but am sure Monty knows better!

Ok Thank you Kildermorie :)

Iris Baby Blue is a form of I setosa.
Our I. setosa flowers early in the year, when was yours in flower? That would determine to some extent when you divide and replant.
To be honest it is the one Iris I have never needed to split as it has never really made big enough clumps to need it.

well I have only just brought them I have 2 they are in pots..Looks like they have already flowered for this year :)

ok if all else fails read the label..sorry Owdboggy it is setosa...so I just plant them in the ground and they wont need dividing? thanks

They like a moist soil in full sun, but they will take a dryer soil in light shade.
Just to add a point there are a lot of Iris species which are neither bulbous nor have recognisable rhizomes. I. sibirica for one and I ensata for another.
Our native I. foetidissima does not have rhizomes either.

thank you again :) great info !!

Guess who has a garden full of Irises?

:( your rubbing it in now arn't you!! lol

Only by accident. My sister in law's 'boss' was into breeding beared Iris and he gave her a huge number of good, but unnamed ones which she passed on to us. Some of them even survived.

Fantastic :)