The lemons on my tree have very thick skins and the fruit is extremely sour. I live in zone 14. The tree had been neglected for at least 5 years and was badly infested with scale, but that is under control now. I thought that it might be a bad variety of lemon, but my local nurseryman looked at one of my lemons and told me that was not the case. He also told me that thick skins and sour fruit go together and are both symptoms of a tree that is starved of minerals. He then sold me and iron, sulfur, manganese, zinc mixture called F.S.T. I am also feeding it Citrus food.

Well I have been tossing down a handful F.S.T. and citrus food once every 6 weeks for about a year now, but the lemons are still horribly sour and the skins are still thick. Much of the roots are under our lawn, so I have been spreading F.S.T. and citrus food on my lawn as well, but it doesn't seem to hurt it. Our soil is heavy clay. It may just be that it takes a very long time for the F.S.T. and citrus food to work its way down, but I was hoping for results by now.

Opinions and suggestions please.