I've been searching this forum for answers and I'm sure some prior posters has a similar issue, but after an hour plus I can't find the help I need.

Here's my dilemma...

I have 5 container dwarf citrus trees of which only one bears fruit. I have 2 navel orange trees, one blood orange and one ponderosa lemon all of which were purchased at a local nursery here in St. Louis, MO. He got them from a dealer in Florida, who I don't know. I also have a key lime tree which was purchased on e-bay. I purchase all the trees in 2006.

Only the ponderosa lemon has bore fruit. It bears 1 lemon per year. It does however get plenty of flowering buds several times a year, but they all seem to fall within a few weeks of flowering. Just 3 weeks ago I counted over 20 flowers, all except two have fallen off. The two navel trees get one or two buds per year but they fall of shortly after flowering. the key lime and blood orange have never produced a bud.

I'm in zone 5 and I bring the trees inside around mid-late October. I don't have great access to natural light inside during the winter so I use a florescent lights for plants which I purchased at home depot. The lights are timed to stay on 10 hrs/day. I water the plants during the winter about once every 3-4 weeks allowing the soil to nearly dry before each watering. The pots all drain well and are 16-20 inches. When the trees are outside they get 8-10 hours of sunlight a day, in southern exposure and are watered about 2-4 times a week depending on how hot it is (In April it might be 2 times, in July and August 4 times.

Initially I used a fertilizer recommended by a friend who also had a couple of citrus trees. It was a 2-1-2 fertilizer, which I realized recently was not effective. For the past 6 months I have use Espoma Citrus-tone 5-2-6 organic fertilizer. I just applied it for the second time a few days ago.

The leaves are healthy and green, although in the winter months when the trees are inside they shed maybe about 1/3 of them.

I tried to be a thorough as possible so you can have a clear understanding. I do have pictures but I can't figure how to include them in this post I just can't figure out why the trees are not producing after all this time.

HELP!!!!