Culture
Best grown in acidic, humusy, well-draining soils in part shade. Fall or spring is the best time for planting in warmer climates. Place in light to moderate shade, preferably with minimum competition from tree roots. Gardenias resent root disturbance. Use fertilizer for acid loving plants, and use iron compounds. Add plenty of organic matter, such as compost or ground bark to as large an area as possible. Mulch plants instead of cultivating. A good time to feed gardenias in these warm areas is mid-March, using an acid plant food, fish emulsion or blood meal. Fertilize the shrubs again in late June to encourage extra flowers on everbloomers or faster growth of young shrubs. Do not fertilize gardenias in the fall. Doing so will stimulate tender growth. Prune shrubs after they have finished flowering to remove straggly branches and faded flowers. Water gardenias regularly. Drip irrigating the shrubs will keep water off the foliage and blossoms and prevents leaf spots.
Gardenias can also be grown in colder climates as container plants in conservatories or greenhouses. If kept as a houseplant, they can be moved outdoors for the warm months, and brought back indoors before the first frost. Grown indoors, these plants need bright light and moderate temperatures (cooler during dormancy), average to high humidity and well-drained, acidic soil. Water moderately, using room temperature water, when possible. Do not allow soil to dry out or stay too wet. Prune after flowering to maintain the plant’s shape and remove faded or brown flowers as they appear. Fertilize from March to August with a mild acid liquid fertilizer.
Noteworthy Characteristics
Gardenia is a genus of roughly 130 species of shrubs and (rarely) small trees native to tropical and subtropical Asia, Africa, and the Pacific Islands. They are characterized by having evergreen leaves and white or cream colored flowers that are often showy and fragrant.
Genus name honors Alexander Garden (1730-1791), Scottish physician, botanist and zoologist who settled in Charleston, South Carolina in 1752.
'Leefive' is a hybrid gardenia cultivar that features a columnar growth habit and large, fragrant blooms. Mature plants will reach around 3-4' tall with a 2' spread. The evergreen, broadly ovate foliage has an undulating or crinkled appearance and will reach around 2" long and 1.75" wide. The main flowering period is in spring, with intermittent blooming through fall. The blooms will reach around 2" wide and have a strong, sweet fragrance. Commonly sold at nurseries and garden centers under the name DIAMOND SPIRE. This plant is protected by patent number PP32516.
Problems
Problems include powdery mildew, leaf spots, dieback, anthracnose, sooty mold, whiteflies, mealybugs, scales, aphids and spider mites. These insects are often serious pests. Hard water, lack of iron or too alkaline soil will produce yellow leaves (chlorosis). The loss of buds or black leaf tips are usually due to changes in temperature or amounts of water. Temperatures below 60°F can produce malformed buds.
Uses
Shrub border, foundation planting, formal or informal hedge. Site plants near entry ways or paths so that the fragrance can more easily be enjoyed. Large container plant for greenhouses or conservatories. Houseplant.