Citrus trees losing leaves
I see that a big difference in temperature can cause this problem, but I live in Virginia. I had my trees outside this spring, summer and fall and they did fantastic. My orange tree had been inside for a whole year before this summer and didn't grow at all. I put it in a pot and sat it outside and it's almost outgrown its pot. The lime tree lost its leaves before I brought it in, but the lemon tree grew hundreds of buds and flowers. The weather has gotten cold, especially at night. I can't leave them outside or they won't make it. Is there anything else I should do to help them through the winter?
The leaf drop can be due to watering issues, fertilizer or disease.
Here are some great articles that will help you.