I would wait until after bloom next spring.

In a cold winter area like yours, you should wait until after bloom next summer and do your dividing then. Make sure you get all irises back in the ground *at least* 6 weeks before the first frost to give them time to root in before winter. In fact, the earlier in the summer you get them divided and replanted (immediately after bloom), the better.

You needn't worry about mulching established clumps for winter. It might not be a bad idea for new transplants through their first winter, but it's just not necessary for mature, established clumps.

In early spring before temps reach 70 degrees, do a thorough garden cleanup around the irises, removing all old iris foliage, leaves, weeds, and other plant debris. Trash or burn the cleanings. Do NOT compost. If the iris planting has iris borers (WI is borer territory), a thorough cleanup will remove many of the borer eggs before they have a chance to hatch next spring (70 degrees is the temp at which borer eggs hatch).

Happy irising,

Laurie

Thanks for the tips, on clean-up as well as plant division! I already divided a small patch last week and will mulch and hope they make it. Will wait until next summer to divide the others.

I have a bunch of rhizomes that I didn't replant yet (tons leftover--not sure where to put them) that are sitting in the garage. Anything I can do with those to save them for next year, in case the replants don't survive?

Hi,

Just saw other question re: overwintering and the response. Ignore question above!

Careful with mulch. You could rot them. Pine boughs are the mulch of choice around iris. Allows the air to circulate. Few people mulch iris at all ever. If they do it's very light or they pull it away from the plant itself. Iris really don't like constant moisture. Anything that is going to hold real moisture is likely to cause a problem. Further east you go the more of a problem. Personally I'd put a dark rock on the them to hold heat and prevent heaving. Mulching would be the kiss of death here.

Experiment a little you might figure out what works in your area. If you already have some that weren't disturbed much you have a failsafe. I've tried cold frames, foundation plantings, rocks, mulch. Potting them in a cold room works best this late. Others worked Ok. Potting worked better.

New England is also very wet compared to WI.
All my iris except for a few extremely tough oldies are in raised beds or have drainage trenches dug around them. It's going to rain here now any time from Now until snow and then most of April and May. I will be redirecting water and snow run off until the end of June. Last snow usually disappears here around May 1st.

Temps aren't usually a problem once established. Moisture in late fall and spring is. Best mulch is good snow early on before the frost goes too deep. I hate snow but find myself praying for it from the end of October on. Got rain?

These things will be lucky to survive! First I divide too late, then I want to mulch them...thanks for the help. I will look for pine boughs. Can't get enough big dark rocks--the bed is roughly 5 square feet, in a curvy shape. I think they will need something. It was very dry here all summer and we've had average rain last few weeks--not all that much.

For the leftovers, the winning suggestion seems to be potting some and keeping them in a cool room. I think I'll split the difference and take chances w/ some in a bag in the garage and some in pots.

Rather than putting any in bags, hang them from your garage ceiling in mesh onion bags. They need good air circulation to prevent them from rotting.

However, I highly recommend you pot as many as possible and keep them above freezing (and only lightly watered) all winter. I have tried to overwinter bareroot rhizomes in my unheated garage overhang. None survived.

Laurie

laurie--thanks. If potted, where would you keep them?
In basement (prob. mid 60s) but dim
in refrigerator--cool, above freezing, dark
in the house--warm, light?

Nicole

I have successfully overwintered potted irises in the house in sunny windows or under lights in my basement. The only significant problem I've encountered in so doing is aphids, but they are easily controlled if you check the plants daily.

Laurie

well after reading this post several of my problems are solved. The bed of irises I didn't get moved I will dig up, toss in wheel barrow, place in basement. Eventually I will get around to cleaning and potting then up. This solves the second problem.... all those excess pots I have been keeping and wondering what to do with.

I kept many plants in basement under lights last winter with good results so a few dozen iris added in should be fine. The temp in the dead of winter in the coldest areas is about 40 degress so it is very cold but above freezing. I can raise the temperature by opening a vent from the furnace but usually don't unless i'm working down there.

Hello!
I have to join in and say thank you to all who contributed. I thought that I was crazy potting all the bearded iris that I bought late in Sept to get them through the winter. I intend to put these under my plant lights in the basement along with my geraniums that I carry over in the winter. Then I'll plant 'em for good in the spring.
Just one question. What type of soil do you use for potting?

Mary

Mary,

Use something light and quick-draining like potting soil mixed heavily with perlite and/or sphagnum peat moss.

Laurie

Hi Laurie:
That's what I used for some of them already. Thanks much.
Mary