Over 2,300 camellia (Camellia spp.) cultivars are registered with the American Camellia Society, many of them from the popular Japanese camellia (Camellia japonica) and Sasanqua camellia (Camellia sasanqua and two closely related species, Camellia hiemalis and Camellia vernalis, both hardy in U.S. Department of Agriculture plant hardiness zones 7 through 9) groups. Some camellia varieties are adaptable to everything from drought conditions to cold climates, with bloom-time ranges from October to April, depending on species and cultivar.
"Some Japanese camellias, around the emperor's palace in Japan, are known to be more than 500 years old," according to horticulturists at Clemson University Extension.
The rose-like flowers of Japanese camellias are a welcome sight in the winter months when many flower species are lying dormant. Camellia leaves are always bright, glossy evergreen, but the flowers range in color from white, through many shades of pink and red with variegated colored varieties of each. Bob Hope (Camellia japonica 'Bob Hope') has large, deep red, semi-double ruffled flowers and bright yellow stamens; it is a mid-season bloomer, flowering in winter, and thrives in USDA zones 8 through 10. Carter's Sunburst (Camellia japonica 'Carter's Sunburst'), also hardy in USDA zones 8 through 10, has pink and red-streaked variegated flowers that also come into bloom in the winter months. Depending on the cultivar, Japanese camellias are hardy throughout USDA zones 7 through 10.
This species group of camellias vary in form from dense, bushy, upright plants to low-growing, spreading varieties. Their leaves are smaller than Japanese camellias, and the flowers are exceptionally fragrant. Camellia sasanqua 'Chansonette' can be grown in USDA zones 7 through 10, with a blooming period of fall through winter with pink, double-petaled flowers. It is a low spreading ground-cover camellia with a height of 2 to 3 feet and 8 feet in diameter. Bonanza (Camellia sasanqua 'Bonanza') thrives in the same hardiness zones with bright scarlet peony-form blossoms early in the bloom season, in autumn. Depending on the cultivar, Sasanqua camellias are hardy throughout USDA zones 7 through 10.
Long Island Pink (Camellia x 'Long Island Pink') is a camellia hybrid that produces single-petaled pink flowers in fall. It is a slow-growing bush that reaches 10 feet in height and 8 feet in diameter in USDA zones 6 through 9. The glossy green foliage emerges in bronze, and this camellia species is often used as a hedge, or as an espalier plant along a wall. Another popular camellia hybrid is the pure white-blossomed Quintessence (Camellia x 'Quintessence') which thrives in USDA zones 8 through 10 and does well as a small shrub or ground-cover. Its single white flowers with pink blush at the petal margins generally bloom early to mid-season, October to December. Depending on the cultivar, hybrid camellias are hardy in USDA zones 7 through 10.
Camellias set more buds than come open, but under-watering may cause bud drop or buds that fail to open and bloom. Bloom failure may also be caused by too much direct sun or harsh winds. Camellias prefer growing conditions that offer filtered sunlight, such as given by the canopy of a large tree.
Blossom failure may also be caused by fluctuating temperatures. If the temperature drops to freezing, cover the camellia bush with a light blanket or heat-retaining plant cover. Secure it at soil level to take advantage of ground heat, and remove cover in the morning.