Temperatures beyond 95 degrees F aren't suitable for plants. Even when the outside temps are in the mid 80s, the greenhouse temp could rise beyond 100 degrees. Ventilation on the walls not facing the sun can allow hot air to escape. When temps rise above 104, natural ventilation won't work without the help of shades and covers.
Utilize shade houses or light deprivation covers to block some sunlight, and minimize the heat transmitting to your plants.
