We embarked in a greenhouse, or my husband did. We really liked the one we bought at http://cookingfirewood.com but we have a question. We read a lot about them getting super hot in the summer time. What can you do or grow that loves the really high temperatures?
Depends on so many things Many greenhouses have vents with automatic systems for opening and closing the vents as temperatures change. Any properly designed greenhouse has vents, whether automatic or manually operated.
There are plants that really like high temperatures, but greenhouses can get too hot even for tropical plants. And if you are wanting to have plants in there year round, then you have the concern of how cold the plants can get, not just how hot.
As has been posted already by Miles and Peter, Most greenhouses have vents and doors that can be opened to regulate interior temperatures.
There are also "swamp coolers", evaporative cooling systems that can help reduce interior temperatures in greenhouses. Also shade cloth that can be moved back and forth is a good way to help reduce summer temperatures.
You do not show where you are located, but I will use my location as an example.
Central Arkansas has a combination of High summer time temperatures (90's to 100+) in combination with high humidity (75-95%)
For green houses to work well in our summers you have to have ventilation and cooling along with shade cloth.
Most summer use green houses here have two roof vents per ten feet, doors at both ends and at least one evaporative cooler but most have two.
High tunnels work here and I know of a few that have removable ends for added ventilation in the summers along with side walls that can be raised for added air flow.
Even the Orchid growers here have all of the above with the addition of true air conditioners, with out these the interior temps can reach 150 f. at a humidity level of 100%.