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.