Answer: Citrus trees can grow indoors and many produce fruit. Blossoms are a good sign and while they are generally self-fruitful, you can help things along by transferring pollen from one open flower to another. Do this with a small artist's paint brush. Even if there is only one blossom open, you can make sure the pollen falls from the stamens onto the stigma by gently brushing the inside of the flower with your brush. If your tree is strong enough to support all of the fruit it begins to develop, they will hold on to maturity. If the tree cannot sustain its health and develop fruit, it will drop the fruit. Since there are only 8 leaves on the plant, it may drop some of the fruit, so be prepared for a smaller harvest.
If your tree does not receive several hours of direct sunlight, you can supplement the natural light with artificial lights. Either fluorescent lights or specialized Gro-Lights will work. Don't use regular incandescent lights, though. They put off too much heat and can burn the leaves on your tree.
There are specialized citrus foods on the market that contain trace minerals that your tree needs. However, since it is in a container, be sure to use less than the recommended amount of fertilizer or you could burn the roots of your tree.
I have good success by using a half-strength dilution of liquid ferilizer (20-20-20) and I apply it every 3 weeks. This provides a constant source of nutrients to the roots of my containerized lemon tree.
Best wishes with your tree!
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