I have a lemon tree that i moved outdoors since it was getting warm last weeek, but now this week's lows are suppose to hit 28 to 30 degrees, could i leave iy outside safely without it dying?
It kind of depends on how old the tree is. If it has been inside with relatively constant temperatures, then exposing it to extreme temperature changes will shock the tree. The damage would appear first on the growing tips and them later leaf loss.
Maybe you could put a tomato cage over the pot and toss an old sheet or something over it for a night or two and that would help.
Citrus can tolerate some freezing temperatures ok...as long as they aren't too extreme and too long in duration.