Answer: Unfortunately this is a bit of a dilemma. The bougainvillea can be kept as a flowering houseplant over the winter if you have a very bright window or heated greenhouse. Alternatively it can be kept in a slightly cooler location and allowed to go dormant, with the soil nearly dry, until spring. It will defoliate and look terrible but should survive. (If it has been exposed to night temperatures in the fifties it may already have begun to slow down for the winter.)
The gardenia is much more difficult to overwinter indoors. It requires a very humid atmosphere and very bright light indoors. A tray of water soaked pebbles can help humidify the immediate area. Aim for daytime temperatures near 70 degrees and nights at about 60 degrees. The soil should be kept evenly moist but never soggy. Do not fertilize it during the winter months while it is indoors.
When you move them indoors, do so gradually over about two weeks so they have time to adjust to the inevitable reduced light levels. (Protect them from cold nights.) Also check them over very carefully for pests prior to bringing them indoors.
Best of luck with your two plants!
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