| Goodmorning to you too Josh! Well, let's face it. This is one slow moving forum..Trying to pick peoples brain I thought would livin it up, make it fun, get more people involved..But not so... It was sort of a trivia question..
It is simple. The key to the problem was at the start of this thread..Sort of kind of a hint..ROOTS You are right Josh..You win..Root impairment from Cold Response! When you have such a drastic flucuation in temps, especially when temps drop at night, just for a plant to be struck with heat and sun by day so rapidly, the roots will not provide moisture, or a drink fast enough under this type of condition, causing dehydration of the leaves.
They are to cold to keep up with the heat. In a sleep like state... It happens everytime my greenhouse gets cold at night, and then when I forget to open the doors and it gets very warm at day.. It also happens if my plant room should get cold by night, then when the heat accidenlty comes on by day, or when the sun heats the room drastically, causing my citrus tree leaves to curl until I either, 1.Lower temps of the airmass in there by day, 2.Throw a shade cloth on it to block the sun,or 3.Raise the temps in there at night so the roots stay warmer and are ready to provide moisture to keep up with the heat by day. So many of us quite possibly may be facing this, especially in our homes with all the dry warm heat, hot window sun, and less than ideal temps at night to make for a perfect growing enviroment. Roots should be above 65 to avoid this issue by night, to match very warm temps by day, unless you plan on storing them in temps much cooler by day to match the cool temps by night.. It is good to know that this "leaf curling" problem is not always just caused by pests, or overwatering.
This is why I forwarn people not to water their plants at first signs of these symptoms, especially this time of year as a first solution, for fear there may be plenty of moisture in the soil down there,or container, and further cause damage by bringing on a case of fast root rot.. A perfect example of this is what happens to my "hydranga" bushes. If it is a cold summer night, they can not handle the very warm day to be followed. All their leaves will wilt and curl all day, until the temps cool, or the sun moves away from them. This after a few days of rain.
In fact, a few of my citrus did this outdoors after days of rain and cool temps everytime, followed by a warm sunny first day. The last thing I was going to do was water again. And their were no pests..:-) Only thought "we" would share. My friend who has been growing citrus sucessfully for years here, a citus expert from 4winds, my dad, and I. Moving on, Mike..:-) | 
