Do greenhouses need cooling? why ?
I know that greenhouses are build to grow vegetables during winter but do they need cooling too ?
Yes, Greenhouse needs cooling. I am sure you already know that a greenhouse may cook plants during the summer but even in winter when it's sunny your greenhouse might heat up to an extent that is damaging for your plants. So it is best to have an automatic ventilation system for your greenhouse. You can follow this easy DIY tutorial on how to install a cheap automatic ventilation system for your greenhouse.
However, during summer if you want to grow inside your greenhouse I will strongly recommend a good ventilation system and if your area gets to much sun then I will recommend using shade cloth for your greenhouse plants. Also the selection of plants is very important. For more details, you can check the following articles: