I mentioned in an earlier post that the plants seemed to droop and then respond by the leaves perking up to watering and feeding...or so I thought. I then noticed that the leaves still droop once per day...always towards the end of the day..whether the soil was bone dry or wet. So I did little reading and discovered it is something called "circadian rhythm".
This is no doubt old news for experienced growers..but for a newbie like myself i was starting to think I was doing something wrong.
More here:
http://www.plantcell.org/content/18/4/792.full