Q.frost on gardenia
I have a winter frosted gardenia that has green growth/leaves on the underneath of the plant but lots of brown outer leaves as a result of winter. Should I trim the brown leaves/branches off or just leave as they are? I have just fertilized the plant.

I am sorry to hear about your plant. This cold has damaged many plants this year. The leaves will regrow as long as the stems are still alive, but it will take some time. Whether you keep them or replace them really depends on how soon you want the plants to look nice again. These articles will help you:
https://www.gardeningknowhow.com/plant-problems/environmental/how-to-tell-if-a-plant-is-dead-and-how-to-recover-an-almost-dead-plant.htm
https://www.gardeningknowhow.com/plant-problems/environmental/tips-for-saving-cold-damaged-plants.htm