Some of the iris I had die were ones I have had for years and years - my mother planted them when I was a child, and they survived those winters where we had -20° as the actual temp for weeks at a time. I thought we had plenty of snow for protection. I know the temperature flucuated a great deal.

Haven't noticed anything else out of the ordinary.

Anyway, I know it is hard to lose plants - especially sentimental ones.

When I divide my iris, sometimes they don't do so well if I do it too late. I usually do it in August and then use a 0-10-10 fertlizer.

I just was doing a review of my garden woes & surprises as Spring is coming to an end when I saw your post ... trying to figure out last Winter, her ++ & -- ... very mixed, was my conclusion! Mama Nature always has the upper hand ... what she takes with one hand, she coddles with the other!

I too, thought both of my Butterfly B went to heaven, later than their late nature, 2 little stems, quite a distance from the original clump, finally greened up & is branching slowly, Clethra/16 Candles only 2 branches leafed out ... even the indestructible, 36' long-retaining-wall, of very old Baltic Ivy looked so pathetic, it was a feat, pruning & clearing much of the dead, very long vines - I've never had to do this in the past ... & yet the other half (40' long ret. wall) with much younger, slowly crawling Climbing Hydrangea didn't think last Winter was an issue & goes about her way!

The colonies of Hostas - hailed those early days of Spring, so I thought, but disappointed at discovering several, attacked by HVX (diagnosed by an expert) - had to dig up & destroy ... I've grown, divided, shared them for at least 25 years ... not the fault of the past Winter ... where HVX came from is ??? a few are still under observation!

Of my painfully, Winterized Hydrangea Serratas & Nikko Blue showed no old cane survival ... my surprise 7 out of 8 are sporting bloom clusters (including 1 variety I was told by an expert may not bloom in our zone) - can't wait to see how the blooms would compare to last season ... a banner year! The Endless S & Forever & E that should bloom on new canes, are slow coming compared to last season. (Except 1) hardy H paniculatas & H quercifolias are all late showing clusters compared to previous years as well.

Lavender clumps (protected with leaves) - lost 1, half nearly died the other half are more beautiful than ever ... I was even able to separate from mother plant a couple of rooted branches I pinned to the ground a couple of yrs ago. Iris had less blooms, Stellas grew like monsters ... would you believe that I almost lost Mint & Sage but a Heuchera that over-wintered in a pot forgotten out there, is as beautiful as all others in ground ... all but 3 of 12 Mums gone! €:(

I know we've had quite a number of fluctuating temps & less than ideal snow-cover for our garden beauties ... the last was baffling! ... Tiny foliage-eating-bugs are a Spring woes for another thread - with all these days of rain!!! €:(

Good gardening just the same ... I'm making lemonade with Ma Nature's gifts & thanking Her for the surprises! €;) Sorry, so long response!

Along with the winter kill that makes recovery such a struggle for the hardiest, dependables/reliables ... also this Spring, ... observing garden allies &/or pesky pests leaving curious looking deposits on some of my garden beauty foliage! €:( I'm glad I learned about the Cornell Univ ext. svc. formula for home-mixed soap-spray to save $$$! €;)

Both of my Butterfly Bushes off shoots (both a ft away from original clump) are now grown to 1.5' & branching out well. All 27 different Hydrangeas survived w/ mixed responses to past winter's effects!

Now that summer is here, things will start looking better!!! Happy gardening! €;)

The plants are growing like weeds, of course... I wish I had their heat/humidity tolerance! ;)