Typically these conditions fall between 20°C / 68°F and 25°C / 75°F and no more than 80% humidity, even in tropical and subtropical areas.
It’s no secret that excess heat in a greenhouse can lead to numerous problems including stunted growth, burnt leaves, damaged fruit and even total crop failures. Lack of humidity is another contributing factor to crop problems. If the humidity is too low, the result is excessive transpiration and crop damage. If it is too high, the plants will be prone to attack by fungi and mold.