how big do gardenias get
Bush Gardenias. Most garden-grown gardenias are cultivars of Gardenia augusta. They have a bush-like habit that varies in height from 1 to 6 feet. You can grow the smaller ones in containers. 'Radicans' spreads to 4 feet wide and reaches 1 1/2 to 3 feet tall. You can grown this cultivar as a ground cover.