Answer: You didn't say how recently you planted your new gardenias, but what you describe sounds like transplant shock. Once the roots have had an opportunity to become established, and the plants adjust to their new homes, they will recover. At that time you can prune them back to encourage healthy new growth and a lush, dense appearance. In the meantime, check the soil moisture level to make sure they need daily watering (excessively moist soil can drive out oxygen; plant roots need oxygen as well as moisture - without oxygen they will suffocate). Before watering tomorrow, dig down near the roots to see if the soil is moist. If so, you don't need to water for a day or two; if not, go ahead and water.
Aside from waiting patiently and adjusting your watering schedule, there's not much else to do until your gardenias get their root systems established.
Best wishes with your landscape!
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