Sounds perfect. Are you guys getting close to frost time?

Well I checked and it said October 9 for first frost. The light has changed though, some leaves are dropping, and suddenly it's beginning to feel like fall.

So do you think it's better to put them in some earth in 4" pots, let them stay outside til it gets too cold (below 50 nights?), then put them in that room, or the basement or something? Is the goal to keep them cool? Slightly damp? Out of sunlight?

Or is it better to do that thing I've read about: cut off all the roots, dust them with sulfur, and put them in brown bags?

Where are you located?

Do not keep damp! That much I know. It is my understanding they are soaked once after potting (to settle the soil). Then no more water until spring. Kept in a dark cold place. I've also read of people keeping the rhizomes in paper bags (no soil) in a cold dark place and planting after freeze danger is past.

Copied from a 2008 post:

Abbigail, if you pot them now, putting them into an attached, but unheated garage that won't freeze for a while is perfect. You can also bring them into the house, but they will get leggy (floppy) and you have to watch for aphids on them. Putting potted plants outside for the winter unprotected is worse than putting them into the ground now. In pots, they are exposed to drying winds and freeze-thaw cycles. When I do have things in pots to leave out, I huddle the pots together against a north-facing wall and put straw bales or mulch around them to protect them some. But I wouldn't do that with the irises that don't have any roots growing yet. Do the garage thing, if you can

Thanks for forwarding. I feel better now:)!

I would just plant them out, if it is a good bed with good drainage. I am still digging and replanting iris here. I have planted iris in November and they have done fine, even bloomed the next spring. I am also in zone 5, and our first frost is between Sept 15 and Oct 5th or so. I planted an inch deep, and did keep checking for frost heave throughout the winter. When does the ground freeze, and does your ground stay frozen all winter, or is there a thaw occasionally? Wait, I just realized that I don't even know what kind of rhizomes you are talking about. Beardeds? Sibs? Hmmm?

Bearded, my first Iris: Superstition, Anvil of Darkness, Old Black Magic. I'm just building the bed now. Raised. Probably put some gravel on the bottom, and do some kind of mix of dirt, sand, compost.

Depends on the winter, whether it stays frozen or thaws. Last couple of winters, excruciating cold. People froze in their rocking chairs sitting by the wood stove. May be mild this winter, but never know.

Where are you? Any further thoughts?

I'm in South Dakota. If we have a very cold open winter with a lot of wind, then sometimes the wind can carry away the soil around the rhizomes and they dry out and don't do well as a result. They end up looking like giant arthropods walking across the dry desert. By open I mean periods of no snow cover. Sometimes even the frozen soil sublimates and dries out. Sometimes we are all out watering the trees in January. I grew up in NE Ohio, and the snow would stay mostly, if it fell. That situation is actually easier. Probably best for most plants is if it is cold for the winter, and then warm for the growing season, but we get temps all up and down. Freezing temps are not really a problem, it is the freeze and thaw that heaves the rhizomes out of the ground that is difficult. I am pretty sure it is going to be wetter where you are than where I am. That is why I was hoping your planting area would have good drainage. Who told you that it was too late to plant? You could always try to contact your area extension people for guidance.

I just looked at an article from the Cornell extension office and they say for zones four and five you have until early October.

Oh I read that you have to plant Iris 6 weeks BEFORE first frost...our first frost is supposed to be Oct 8.

I would trust the Cornell Extension. I am no expert, but I think if you get them in soon you will be ok. I live in upstate New York, and I just planted a bunch of Iris rhizomes a couple weeks ago.

Thanks! I just wrote the extension specialist...I'll post the answer.

Mulch your late planting (oak leaves are great!) and remove mulch in early Spring. I usually end planting bearded iris at the end of September. I have successfully transplanted Siberian Iris at the end of October, usually don't push it till mid-October. Zone 4a, continental climate, Minnesota.