What happens to citrus when it freezes?
Correspondingly, do oranges go bad if they freeze?
When the water in fruit freezes, it expands and pushes on the fruit's cell walls, breaking and destroying them. I think we can all agree that frozen fruit is not as good as fresh, but surprisingly, oranges aren't too bad when frozen and thawed.
In this regard, what temperature will kill a lemon tree?
Citrus trees are a tough, durable lot that can take a touch of cool weather. While frost is not likely to kill a healthy, mature lemon tree it can certainly inflict damage when temperatures drop below 29 degrees Fahrenheit for longer than 30 minutes.
Despite some cold tolerance, citrus trees should be covered when freezing weather is expected to reduce shock and increase the chance of survival. Trees younger than three years old especially should be completely covered; keep a frame in place if you live in a frequently cold area.