To answer the original question it seems as tho the plants are just super stressed, and when they get stressed they drop their leaves and fruit to survive. They are getting much different conditions than they were at HD, where they outside or inside a greenhouse in HD? I am going to guess that they were inside or at least shaded, they had to be hardened off in before just putting them in full sun. This is done by SLOWLY introducing them to the sun for a short period of time gradually working up to full day sunlight. Stop fertilizing and watering until you know for sure they are dried out. Than completely soak and repeat the cycle. Citrus will survive slightly dehydrated better than they will flooded. The meter you are using measures the electric conductivity of the soil so if it is littered with fertilizers you will get false readings. Are you able to post pics of the trees and their pots? I would suggest a re-potting and pruning, but as you said you are new to gardening and this may scare you a bit. Do you have any friends with a green thumb that could help you with this? Don't expect any flowers or fruits till next year as said since the plants are so stressed, but you never know with some TLC and luck you may get some winter blooms. Again pics would really help, and good luck!

Dear Sara, Though I have only had my fruit tree for a few months, I have experienced the joy and disappointment on care for .......a PLANT! Don't know why, but want this one to do well. I too had this sticky white stuff. Here in Seattle, I keep my plant 50% of the time indoors, and 50% out on my southern exposed deck. After reading and inspection, I have discovered that my plant has scale, a type of bug infestation that can present. These insects are very small (my the size of a small bead) and they feed off the plant. They look like small pill (potato) bugs and move very slowly. Subsequently, their poo is the white, sticky substance that is deposited on the stems and undersides of leaves. I read this material can attract other insects (ants) but is not toxic for pets. I was able to catch it early, and washed the plant well. Then, I sprayed it with a combination of Neem oil and diswashing liquid solution (you can buy various preparations) and after a couple of days, washed again. Upon further inspection, I only saw 1 bug that I happily squished!! Must periodically inspect and occasionally wash. I don't know if that is what you're experiencing, but if so, it is much easier to treat when infestation is new (vs established). Good Luck!!

. First, when you dramatically change the light conditions a Meyer will drop most, if not all its leaves, to replace them later with leaves better suited to the new light conditions. To move a Meyer from outside to inside without the leaf loss, you need to move it from full sun to partial sun for 2 weeks; then to full shade for 2 weeks; then indoors; reverse the process when putting it out in the Spring... and please DO put it out, if you can; you will be rewarded with a happy, healthy plant. Second, when you bring it indoors to a sunny window, the plant gets warm; but the roots generally stay cool; and citrus roots don't like to grow into cool soil... the solution is to put some sort of heater to warm the soil, or to put the plant a little further from the window. The thing to remember is first the roots grow; and then the leaves and branches. Don't stress about the flower/fruit drop; it is normal for a quite young tree; if you treat it well, you can expect to flower next in the Spring; and likely then it will keep some fruit, or too many fruit; be sure to post photos then, so we can help you.

Then I would guess it has been attacked by Medfly or some other egg laying insect. In experiments with getting Meyer lemons to turn yellow earlier, or in different climates, I found that penetrating the skin with even the tiniest pin would cause the fruit to turn yellow; but it also degrades that fruit and leaves a mark much bigger than the original pinhole. I think that Medfly is supposed to not exist in Florida today; but that doesn't mean it is not there. I would take that fruit to your local agricultural agent to have it checked.