In past posts I bewailed the poor performance of the tomatoes in my greenhouse, with their leaves turning over and changing to a vivid purple hue. All the fixes suggested here had no effect. I was distraught.
Today, just after noon, I was in the greenhouse. I went to check the soil moisture by sticking my finger in the pots. It was moist all right, but it was uncomfortably hot as well. The sun beating on the pots had raised the soil to the temperature of hot coffee (or tea, if you prefer).
Now, I have rigged some heavy plastic board to shade the pots. I await further developments and I will post them here. Thanks to those of you who have kept with me so far.