Posted: 28/01/2015 at 18:52
Jess.........you say your Gardenia was purchased many moons ago as an "outdoor" plant.
If you purchased in the UK, as far as I know the common Gardenia was always grown as a house plant. In the last couple of years, some companies are selling a "hardy" Gardenia but that is very much open to interpretation.
Gardenias are not the easiest plants to keep happy - cool but not cold, light but not sun, damp but not wet.
If the leaves are turning yellow and dropping that is usually a sign of EITHER over watering OR just a natural dropping of leaves at this time of year. It could be that you are misting too much without providing the optimum conditions. Even evergreen plants need a little respite.
There is little point in feeding it at the moment......you need to see some shoots emerging before you worry about that.
If the stems are green and you have access to a Propagator, take some cuttings.
At the very least, don't abandon it now..........wait for natural higher temps and light levels and see if it will produce new leaves/shoots.
Really sorry not to be more helpful but wish you luck