Answer: Taking your citrus trees into a greenhouse for the winter was a good idea; I think they are adjusting to the different light levels, humidity and temperatures, which is why they are losing leaves. As soon as they adjust, they should produce healthy new leaves. I'm concerned that you may be over-feeding your citrus. They are heavy feeders, but a monthly application of 33-33-11 is a bit much, especially in the late fall and winter when they will be growing more slowly. I'd hold off on feeding them until spring. If you want to feed them every month, dilute the liquid fertilizer by one half to one-third. This constant-feed will provide all of the nutrients your citrus needs without the fear of overdoing things.
Best wishes with your citrus trees!
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