Q.Sickly Calamondin (leaf Drop And Branch Die-back)
We’ve had this calamondin for three years. Up until late this past summer it was growing well and bearing a lot of fruit. Then there was a lot of leaf drop (about 75-80%) and then branches started dying back. The branches that didn’t die grew new leaves that seem to be doing okay. It bore more fruit, but the fruit never quite ripened, turned squishy before turning orange. What are my best options for nursing this back? Any suggestions as to cause? During the summer it is sited outside and gets sun for a few hours late in the afternoon. Brought inside for winter when nighttime temps hit about 50F. Thanks!

Certified GKH Gardening Expert
I suspect a couple of issues.
If this is not fertilized, regularly, then this will be a good portion of the problem. Citrus fertilizer that is meant for the purpose will be best, but you can build your own citrus fertilizer if you are well familiar with the requirements.
The next problem that I suspect will be root rot. This is common with citrus, especially, when overwatered during their semi-dormant state.
Fungicides, citrus fertilizer, and proper watering and pruning will bring this back to health!
Here are some articles that will help:
https://www.gardeningknowhow.com/edible/fruits/calamondins/growing-calamondin-trees.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soil-ph-plants.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-moisture-in-plants.htm

Great information - thank you so much for the advice!