Gardenia

Your gardenia, like other plants moved indoors for winter, is adjusting to the change in growing conditions. The lower light, shorter days, and drier air are difficult growing conditions for many, especially gardenia, plants.  Grow your plant in a warm sunny location.  Avoid drafts of hot or cold air.  Move plants to the sunniest, usually south-facing, window.  Supplement the natural light with an artificial light if light is limited and your plants are struggling through the winter.  Increase the humidity by grouping plants together.  Place pebbles in the saucer and keep it filled with water.  The pot should rest on the pebbles, not sit in the water.  As the water evaporates it increases the humidity around the plants.  Leaves of these and other acid loving plants turn pale green or yellow with green veins when the soil is too alkaline (sweet).  Try using distilled water, water from your dehumidifier, rain water or melted snow to water the plants.  These sources of water are more neutral or slightly acidic.  With proper care and some luck you should have a healthy plant and a few fragrant blooms.  Wait until the plants recover from the move indoors and new growth appears to start fertilizing.  Use a dilute solution of flowering houseplant fertilizer for acid loving plants.