Caring for an indoor Meyer Lemon

Question

I’m finding conflicting information on when to fertilize a potted Meyer Lemon. Some sites say not to fertilize during the winter months, some say to fertilize once a month except in the winter months. I bought the Meyer Lemon in June in CA. Moved it indoors in early October placing it in a south-facing window (I live in Olympia, WA) and it had five lemons on it when I bought it. Four of the lemons are yellowing up now. I have not fertilized it since I got it other than to repot it in a larger pot and in a cactus medium. This last month it produced dozens of flowers and I cross-pollinated them with a artist’s paintbrush. New fruits are growing now. There has also been a lot of leaf drop but it’s also producing lots of new leaves. I also set up a red/blue 54W grow-light which I have on 12-16 hours a day. I’ve also been told that’s way too much exposure and the grow-light shouldn’t be on more than six hours a day. I also don’t water it unless my finger plunged into the soil to the second knuckle comes out dry.

So my questions are:
As long as it’s growing (producing flowers, leaves and fruit), how often should I fertilize it?
How long should the grow-light be on every day?
Is it odd to have a lot of leaf drop prior to or just after lots of buds emerge?

Thank you!
Barbara Kam,
Olympia, WA.

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Answer 1

It is still preferable to not fertilize in the winter, because this can lead to spindly, less healthy growth in the lower light levels (indoor light is almost always less intense than outdoor light). If the plant starts showing signs of nutrient deficiency (see the following article), then you can fertilize with the appropriate nutrients.
http://www.aces.uiuc.edu/vista/html_pubs/hydro/symptoms.html

I would say 8-12 hours of light would be fine. 16 hours is probably too many, because you would trick the plant into thinking it's summer. This may be less harmful to a Meyer lemon than to most plants, though, since they flower year-round. The leaf drop is usually related to being indoors, but hopefully it won't lose many leaves.