I gave it half a cup of an organic fertilizer (4-5-4) a month ago and it seems to deteriorate further. The folks who sold me the plant told only fertilize lightly.

Most organic fertilizers require bacteria that uses nitrogen to break them down. The bacteria then die and release the nitrogen. That delay can be several weeks. If you use an inorganic fertilizer it will immediately be available to the plant.

Some people find it difficult to use organic fertilizer in potted plants due to the lack of micros that are naturally in the ground, helping to break the organic fertilizer down.

Nitrogen will leach out of the pot due to the frequent watering that must be done in pots. I would advise using an inorganic fertilizer that is high in Nitrogen to help the plant catch up on Nitrogen. It should show green up in less than a week. I would mix a table spoon of inorganic fertilizer to one gallon of water. After that add 1 teaspoon to a gallon of water per week until the plant is actively growing.

Thanks, I have some general purpose fertilizer 16-16-16. I'll give it a go.

ive noticed something with Longan and Lychee.

they need oversized containers, and they need very active soil (live).

they will not survive in soil-less media and chemical fertilizers. not long anyway.

what is the potting soil ?

Also, trying to produce flowers and fruit put a demand on the nutrients.

Looks too dry. Maybe keep a saucer under it?

The soil is fairly moist I use a mixture of potting soil and peat moss (2:1).