Two different types of damage tho - freeze/thaw is earlier in the season
than heat wave/freeze. The first heaves, the second kills. Both cause
injury, which can lead to rot.
But lush growth, during the peak growing time of the plant, as it's
trying to send up bloomstalks (or after they have already started) seems
particularly susceptible to death - all the energy reserves went into
that new growth and there's nothing left for repair or new growth.
This far south, right about where the winter jet stream 'lives' on
average, we can have weeks of good iris growing weather (i.e., highs in
the upper 70s, even near 90) in the middle of the winter if the jet
stream wobbles north for a while. Then it can turn into mid winter
again, with lows in the single digits.
The southern jet stream seems to be wobbling farther north the last few
winters, 'sharing' the Tennessee experience with Kentucky and even
farther north. And it sure wobbled farther south than usual this spring!
> That type of weather is the real problem; freeze/thaw happens here a lot in early spring.
Linda Mann east Tennessee USA zone 7/8
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