Iris unguicularis Hardiness test
James Waddick (Wed, 22 Feb 2012 12:28:32 PST)

We have just had 2 nights where the temps went down to 6 F
(-14 C) and yesterday barely made it up to freezing. ....
Today the plant looks essentially unchanged, but the flowers
and buds are totally frozen, collapsed and lost. So clearly the
flowers cannot take this extreme, but the plant looks ok.

Dear Friends,
wrote the above (and more) on 2/12/12.
Today 2/22/12 exactly 10 days later, the first of a second
round of buds has opened completely.

So not only is 5 degrees cold enough to kill open and nearly
open buds, but a healthy plant can recover and re-flower in as short
as 10 days.

I must remind readers that this plant is outside and in the
ground, year round in a micro-climate, south facing aspect near a
stone stairway. More buds are visible and I expect to see more
flowers soon.

Todays temp is going toward mid-60s F.

So if you are wishful and in Zone 5/6, give it a try.
Best Jim W.

ps a patch of nearby Iris magnifica had one entire shoot freeze
almost to the soil line while others in light pine straw mulch are
untouched. I am hoping the one with the frozen shoot has an intact
bulb and can produce some new shoots eventually.
--
Dr. James W. Waddick
8871 NW Brostrom Rd.
Kansas City Missouri 64152-2711
USA
Ph. 816-746-1949
Zone 5 Record low -23F
Summer 100F +