Answer: Before you move plants directly from greenhouse to the outdoors, they need to "hardened off". This is a process of gradually introducing them to the elements so they toughen up, Just like us northerners who go out in the sun for the first time after a long, dark winter - we get sunburned badly, and then it darkens to tan, and we don't get burned again - usually! Plant leaves don't fare so well when they get sunburned. Leaves turn white because the tissue dies. Also, a greenhouse is a humid environment. Outdoors, breezes quickly cause drying and wilting of plants.
Before putting plants out, slowly expose them to the sun and wind by putting them out for 1-2 hours the first day, and gradually increase the duration by a few hours a day until they can stay out all day and night. Alternately, you can make a lath-topped table and place plants under it. They'll get dappled sun that way, and you can place something against the walls to protect them from winds. Gradually remove slats from the top and windbreak from the sides as they get stronger.
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