Gardenias are shrubby, flowering plants that -- like bedstraws -- belong to the Rubiaceae or Madder family. In warmer climates, homeowners commonly use them in the landscape, while in colder climates, gardenias are popular for use as houseplants. Regardless of where you grown them, gardenias add ornamentation and elegance to your space, which is due primarily to the large, fragrant flowers they produce. However, these plants can also contribute color to indoor and outdoor environments with their foliage and fruit.
Of the 200-plus species of gardenias, the majority bloom with flowers 2 to 5 inches wide that are a shade of white or pale yellow. Examples of white gardenias include the 'Coral Gables' subspecies, or cultivar, which produces single-bloom white flowers; the 'Aimee Yoshioka' cultivar, which produces double-bloom white flowers; and the 'Mystery' cultivar, which produces double-bloom, pure white flowers. Double flowers have extra rows of petals that give them a fuller, more layered appearance.
Ivory-colored gardenias include the 'White Gem,' which bears single, star-shaped ivory flowers that have a medium fragrance; 'Kleim’s Hardy,' which bears single, star-shaped ivory-white flowers that are highly fragrant; and the 'Chuck Hayes,' which bears semi-double ivory-white flowers.
Gardenia cultivars also can produce flowers that are white-yellow, like the 'Golden Magic;' creamy white, like the 'First Love;' velvety white, like the 'August Beauty' and white with yellow centers, like the 'Veitchii'.
Gardenia leaves are thick, oval-shaped and grow in an opposite pattern. This mean each leaf appears directly opposite another on a branch. The colors of gardenia leaves ranges from glossy medium green to glossy dark green. However, if temperatures drop below 60 degrees Fahrenheit, gardenia leaves can become dull or lackluster and their green color can fade to yellow or greenish-yellow. Each gardenia leaf typically is between 3 and 5 inches long and about 1 1/2 inches wide.
In addition to bearing colorful leaves and flowers, gardenias bear colorful, fleshy, oval-shaped fruits. Each fruit typically is between 1/2 and 1 1/2 inches long and has an orange outer shell or capsule. This fruit capsule contains gardenia seeds.
Keeping the colors of gardenias brilliant -- regardless of whether these colors are from flowers, foliage or fruit -- requires providing gardenias with ideal growing conditions. For best results, plant gardenias in moist, fertile soil that is well-drained and rich in organic matter. You can increase the organic contents of your soil using several different materials, including peat moss, compost or bark mulch. In terms of soil chemistry, gardenias prefer acidic soil that has a pH range between 5.0 and 5.5. Applying sulfur-based fertilizers to soil can help increase soil acidity.