I have some Dr Feel Good's(in prefower stage at 90 days) and Nirvana AK48 growing in direct sun on 40 c days that show no wilting. High temps, I think are not the problem. Stale air is. Plenty fresh air and moist roots is all I need. The pots should always be dry on top but moist a few cms down.
My advice is to buy a moisture meter(the cheap ones for $10 work well for me) probe from bunnings. Stick it in the soil, down at least a few cms. Keep the moisture always between low and high. I only water when the needle points to the dry end of the reading. I only water till the needle points to the high end but never let the watering point to max moisture on the needle(stops oxygen to the roots, OK if only a few hours on a scorching hot day where the moisture will come down rapidly).
Never over water from too much kindness. The water moisture levels are just as important as PH.
My advice is to buy a moisture meter(the cheap ones for $10 work well for me) probe from bunnings. Stick it in the soil, down at least a few cms. Keep the moisture always between low and high. I only water when the needle points to the dry end of the reading. I only water till the needle points to the high end but never let the watering point to max moisture on the needle(stops oxygen to the roots, OK if only a few hours on a scorching hot day where the moisture will come down rapidly).
Never over water from too much kindness. The water moisture levels are just as important as PH.