With reference to the question on altitude, the natural habitat of quite
a number of irises, particularly Siberian, Scorpiris (Junos),
Nepalensis, etc. ranges to at least 13,000ft ASL. These irises are
living in the very harsh environments found in such locations as the
Himalayan, Pamir, and Alai mountains of south eastern Asia which are
mostly characterised by dry and very bright but short summers; very
windy and very cold winters. Often, their best supply of water is from
snow melt. At the same time, very similar conditions are found in areas
frequented by other irises. Such species as ensata and laevigata in
North and East Siberia are living under more moist conditions but they
still suffer from extreme winter cold, strong winds, and the short,
often dry summers. We recently had a visit from a botanist living on
the far north east coast of Siberia where the total season was about two
months (and we feel badly off in Ottawa!).
I believe that anyone growing irises in North America lives in an area
that is generally much more hospitable than the natural habitat of a
large number of the species of iris. Of course, this may not apply to
Ellen living in the White Mountains of New Hampshire!
Ian, in Ottawa, where my morning glory is still not blackened by the
frost although there were signs that it almost arrive last night.