Help me not kill my MIL's irises

[flymetothemoon]

Yep, exactly like the title says. I'm in MD, zone 7A. We have 4 different irises that are divided from my MIL'S and which were originally from my DH's grandmother. So, I'd like to successfully plant them and not kill them like I did last year's Costco irises.

How deep or shallow should they be planted?
Is a south facing garden bed ok?
Anything special the soil needs?

[simpsongal]

DO you know what kind they are? I googled a lot before doing this but I just dug up and divided a huge patch of 50 yr old irises....I HOPE I did it correctly. I trimmed off the old rhizome and planted them super shallow (watered for a bit....hopefully enough?). They looked pretty paltry but I'm crossing everything that they pop up next year. Everything I read said irises are very forgiving though they could take time to bounce back (that's why there are so many grandparent-gifted patches of them).