Hello. I'm new-I have a 1foot tall actively fruiting recently, C alamondin Orange tree, fed regularly with plant sticks and never repotted in 2-3 years. Purchased at flower show. All of the leaves have turned yellow with dark green veins. I read an article a while back that said citrus trees as houseplants were prone to this and that it indicated it was missing an important mineral, but I didn't save the article. I plan the repot, but what should I add?? Please help. I have already asked about and no seems to know the answer....