I live in Connecticut. I purchased a 3 year old potted Improved Meyer Lemon Tree in May 2013. It was healthy, beautiful and had about 20 small lemons on it. I left it outside until it became too cold in Sept/Oct, then I brought it inside. The lemons were still on the tree, so I wanted to make sure it got sun so they would ripen. When it was at least 50 degrees, I brought the tree outside into the sun. I brought it inside at night because it was too cold. I do not have a south facing window, so it was in a west facing window, which did not get a lot of light due to trees. The house is about 68-70 degrees in the winter; but dry.

The lemons took a long time to ripen. In early January 2014, the leaves began to dry up and fall off the tree. There were about 10 lemons still on the tree, which I removed. I pruned it a bit when I removed the lemons. The leaves started to gradually fall off one at a time over a period of several weeks. Then all of a sudden they all just dropped. The leaves dried out then fell off. They did not turn yellow first. By the end of January, it had lost all its leaves. I tried to create more humidity by placing a plastic bag over it, but it started to develop some mold, so I removed it.

During the winter, I watered it about once per week. I sprayed it with water every couple of weeks. I did not fertilize it. In March, 2014, the tree started to show new growth, but only on a few limbs. By April, there were 2 blooms on the tree, both eventually fell off. In early spring during warm days, I brought it outside to get more sunlight, then brought it back inside at night. In April, I fertilized it with an all-purpose 10-10-10 every two weeks.

It is outside full time now. Also gave it Alaska Fish Fertilizer 5-1-1. Did not seem to respond to this. Noticed small very faint looking webs between branches and leaves. I used Bayer Advanced Natria Insecticidal Soap as I read this issue may be spider mites. Its new growth is sparse; it did not blossom; it does not have vibrant green leaves; some of the leaves are yellowish; and does not look healthy.

Can anyone advise a regimen for this tree?

This link has several pictures of the tree and leaves.

Here is a link that might be useful: Meyer Lemon Tree pictures on Dropbox