If you are growing your Gardenia as a potted plant indoors, keep it out of direct, hot sun, and allow it to only get bright light. I think that your 'black mold' is more than likely an algae growth, which is a cosmetic problem for your plant rather than a health problem.
Monona is a city in Dane County, Wisconsin, United States. The population was 7,533 at the 2010 census. It is completely surrounded by Madison and is part of the Madison Metropolitan Statistical Area.
Ravenna is a city in Portage County, Ohio, United States. It was formed from portions of Ravenna Township in the Connecticut Western Reserve. The population was 11,771 at the 2000 Census and 11,724 in 2010. It is the county seat of Portage County. It is named for the city of Ravenna, Italy.