Q.hibiscus turning yellow
I have 2 hibiscus trees about 8-10 foot apart. Both planted the same day. The one tree is thriving, while the other’s leaves are turning yellow. Same sunlight, same watering, etc. Any ideas as to what might be the problem turning yellow?

Inspect the struggling plant carefully. Any signs of insects?
If the plants are newly planted, one may just showing more stress than the other.
You may need to add more water to the plant that is struggling.
Here is a good article that with information.
https://www.gardeningknowhow.com/ornamental/flowers/hibiscus/how-to-care-for-hibiscus-plants.htm