85 maximum for besseas...use a DIY evaporative fan , very easy and should bring temps down by 10 degrees. My setup is a box fan between outside and inside (lower part of greenhouse). I have it connected to a thermostat when the temp hits 85. Even with the temp outside of high 90's ..it works...but you also need to have the FLOOR of the greenhouse WET. The forced air (which is exhaling to outside the greenhouse) will create a good breeze in the GH and the evaporation of the wet ground will lower the temperature. ALso, place a covering (like a sheet or thin plastic) in front of the fan (outside part) , this covers the fan when its off at night and of course the forced air blows the covering up when the fan is on.