I purchased a gardenia plant on May 5th for Mothers Day. The plant soil was very dry so the salesperson told me to water it when I got home. I did as she said using about 1/2 cup of water. I always have jugs of water for plants only so that the temp of the water is right and the quality is better. I have never had a problem with any plants dying. On the second day, the flowers started turning a light yellow. By the end of the day, they were almost like marigolds. The next day the leaves got dull looking and within 5 days, the plant looks and feels dead. Everything is very dry and leaves falling off everywhere. What happened? Thanks so much.
Yellow Flowers and Eventual Death of Plant
Certified GKH Gardening Expert
Gardenia are know as finicky plants, whether they are grown outdoors or indoors.
In the indoor setting it can be especially difficult to meet the lighting and humidity needs of the Gardenia plant.
The plant was most likely stressed from the change in location. Yellowing leaves can certainly indicate a few issues, but in this case it is likely lighting and watering issues.
The plant needs bright sunlight and the soil should be moist but never soggy. 1/2 cup of water was not likely enough to wet the entire root system. It's best to water throughly, making sure any excess drains away, and then water again when the top inch or so of soil begins to dry.
A humidifier is the best way to provide the humidity that the plant needs.
Continue to care for the plant as described and even though the leaves may have dropped, if the plant is still alive it may began to leaf out again.
Here are some links with more information.