Getting through the first summer, an example
Rodger Whitlock (Sat, 06 Mar 2004 14:50:16 PST)
On 3 Mar 04 at 10:41, Jim McKenney wrote:
I have a general observation to make with regard to summer dormancy
in summer humid areas. I have attempted to bring some summer dormant
iris (oncos and onco hybrids) through our humid, hot summers by
digging them and storing the dormant rhizomes under cover but
otherwise in the open air in a shaded place. Something very
unexpected happens: these plants, which endure severe drought in
nature, shrivel up and dry out. Some frits seem to show the same
response here, others don't.
With the iris, bringing them into the air conditioned house seems to
work better; the rhizomes remain hard and ironically don't dry out.
This makes me wonder if the humidity isn't inducing the plants to
open their stomata and lose water - water which is not replaced by a
dormant or non existent root system.
Is there a plant physiologist out there who can explain this better?
An educated guess from a chemist:
Something similar happens with cyclamen in pots. Unless you are
careful to keep the soil slightly moist, the tubers wither during the
summer. As a result, they are quite tricky to bring back to life, in
many cases simply rotting away when our fall rains come.
Rex Murfitt has told me of visiting a cyclamen guru in Britain who
grows his plants in tall (ca. 12", 30 cm) drain tiles and keeps them
sitting in a quarter inch of water all summer long.
My guess is that these plants have a perennial root system which is
constantly imbibing moisture, unlike, say, narcissus or crocus where
the root system in annual and the bulb has no water uptake during
dormancy. Certainly established cyclamen turn out to have a very
extensive root system if you dig them up or decant them from a deep
enough pot.
--
Rodger Whitlock
Victoria, British Columbia, Canada
Maritime Zone 8, a cool Mediterranean climate
on beautiful Vancouver Island