Newly Formed Lemons Dropping From Tree

Question

Having purchased a lemon and orange tree last year, I have found that in each summer very soon after the fruit has started to form they drop, leaving no maturing fruit. The trees look to be in good condition with no discolouration of the leaves, with very little leaf drop. They are planted in large pots approximately 16 radius by the same high. They are outside in the summer and brought indoors in Oct. and given a citrus feed about once a month. The garden is south facing.

Answer 1

This will answer some of your questions:
https://www.gardeningknowhow.com/edible/fruits/citrus/citrus-blooming-season.htm