My freshly planted blue hibiscus has a limp look and some yellow leaves falling off.
Transplanted Hibiscus Limp and Yellow
Certified GKH Gardening Expert
The soil will need to be kept moist but not soggy. If the roots dried out, the plant will suffer greatly, and possibly not survive.
Make sure the soil is well draining, if the soil does not drain and the roots sit in water, the plant also will die from root rot, or develop a fungus.
Make sure you have planted in a full sun location. Your plant needs a good 6 hours of sunlight.
Make adjustments to the watering and wait and see.
You can prune back the plant, by 1/3 to help it recover.