They are the "Prima Donnas" of the garden world. Gardenias grow very well in Florida. Everybody seems to have one or two. That's the environment Gardenias like most - very warm, consistently moist & do best in a well-drained, humus-rich, acidic soil, lots of humidity, as much sun as you can give them. Avoid cold water, cold drafts & sudden temperature changes. They don't like to be moved around very much. Find a place for them to live.

This plant is tender - it can be put outdoors for the summer months, once all risk of frost is past,but must be under glass (greenhouse or conservatory) to get through a winter in the UK. More info here

https://www.rhs.org.uk/Plants/7605/Gardenia-jasminoides/Details