Are Dutch Irises hardy to USDA zone 5? Any one grow them in that zone?
Shoot, nobody from your zone has answered. Have you seen them growing in your area?
Your US zone 4 is the borderline zone. If you have a sunny bed beside a chimney that is where they would have the best chance to winter over (with lots of mulch).
I have seen some growing and blooming last spring here in South Dakota along a foundation. We are zone 5, but we had only -5 F as our lowest temperture last winter, and that wasn't for very long. It was unusually warm. Usually we have a week of lows in the -20's. Also, I don't know how long they have been planted at that location as I am new to this neighborhood, but it is a large clump.
I have had ZERO luck with Dutch iris and I live in Connecticut. What is the trick?
Here we plant them deep(8) and be sure to fertilize with bulb fertilizer. I always plant at least 5 in a hole. When I used to enter arrangements in a show, I always used them instead of TB'S.
I have resorted to growing a few of them indoors! We will see if they can bloom for me in my bedroom.
The rest are outside. 8 inches? That is worth a try if mine again fail me.
The first year I tried them I thought I had done them too deep. They only had small stringy leaves popping up.