We bought a lemon seedling off of a gentleman with LOTS of tall lemon trees here in San Antonio. We have raised it over several years from a tin can to big pots, to the biggest barrel we could find. We bought a home 6 months ago and were finally able to put it in the ground. The first 3.5 months went just fine. Now, it's leaves are droopy no matter what. And parts of the tree is losing leaves and just looking generally unhealthy. This is our baby and the only plant we have ever kept alive!! Lol. Also: 1. It has never bloomed in 4-5 years but we figured we stunted its growth too 2. We heared they needed some pollination (cross pollination?) so we planted a blood orange tree around the same time we put this one in the ground. 3. With the exception of a tiny ant looking insect here and there I haven't noticed any infestation.
Certified GKH Gardening Expert
These can be a little tricky. From the looks of it, the tree lacks nitrogen. A high N (nitrogen) fertilizer will help bring back the color. Also dolomitic, when applied to the sol, will keep the pH from swinging on the alkaline side, which will also harm the tree. Make sure the trees receive plenty of water.
Here is an article for more information on caring for citrus: https://www.gardeningknowhow.com/edible/fruits/citrus/fertilizing-citrus-trees-best-practices-for-citrus-fertilizing.htm