Most greenhouse sliding doors do not come with latches. A simple latch picked up from the hardware store will go miles for keeping your door shut and secure. Just look at the door and select a spot next to a cross support bar and attach it.
My greenhouse has a storm door, but even that was not safe from the wind. On a breezy day, I was carrying supplies into the greenhouse and the wind caught the door and severely bent the door closer mechanism to the point where the door would not shut without removing the mechanism all together. After replacing the mechanism, we added a security chain that would prevent the wind from hyper-extending the hinges and door closer.
Louvers and shutters can cause problems all their own. We use them to keep pests out and regulated air in, but in windy areas, make sure you select a shutter made from a sturdy material. My first shutters were plastic. The wind made quick work of that! The shutters broke off and cold air rushed inside the greenhouse. I strongly suggest using metal shutters.
Just a few little precautions can keep your greenhouse structure in tip top shape!
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