Hardiness of Camellias in Winter

Background

• Asian imports, camellias produce large showy single or double flowers on evergreen shrubs that can live for many years. The American Camellia Society lists more than 2,300 varieties that include the most commonly grown Japanese (Camellia japonica) and Sasanqua (Camellia sasanqua), as well as a vast array of hybrids that include Camellia reticulata and Camellia salvanensis. Japanese camellias can grow from 12 to 25 feet with 4-inch-long dark green leathery leaves. Flowers measure up to 5 inches in diameter and can be white, pink or red. The smaller Camellia sasanqua grows from 1-1/2 to 12 feet and its very fragrant flowers grow from 2 to 3 inches in diameter against smaller darker-green leaves.

Culture

• Camellias are slow-growers and are damaged by even the lightest frosts. They need soil that is well-drained and rich in organic matter and with a pH range of 5.5 to 6.5, which is slightly acidic. A soil test is the best way to gauge the soil's pH as well as other nutritional deficiencies. In USDA zones 7 and 8, camellias are best planted from mid-October to November for spring flowering, or mid-March to mid-April for fall blooming. They prefer partial sunlight but sometimes do well in full sun once the plants have leafed out enough to provide shade for the roots. Camellias need enough water at planting time to help them get established as long as it doesn't saturate the soil, which leads to root rot. Unless a soil test indicates the need for additional phosphorus, no fertilizer is usually needed at planting time.

Cold-Hardy Camellias

• After disastrous winter storms from 1977 to 1979 killed more than 950 camellias in the U.S. National Arboretum in Washington, D.C., the arboretum's horticulturist William Ackerman was able to produce a new cold-hardy cultivar that could be grown in USDA zones 6a and 5b, which is as far north as southern Maine. Working with Camellia oleifera and other cultivars, Ackerman hybridized a new cross that was called "Lu Shan Snow" in honor of its Chinese origins. The new cultivar tolerates temperatures to minus 15 degrees F, and since then, other cultivars have emerged from crosses between "Lu Shan Snow" and other less-hard varieties. Northern gardeners are advised to mulch camellias at planting time and to maintain the mulch year-round to insure the plant's survival. A 2- to 3-inch layer of mulch not only protects the roots from the cold, but it also shades them during the warm months and helps conserve moisture.

Hardiness Zones

• The USDA developed the plant hardiness zone system as a source of information on how much winter cold plants can tolerate. The system is a boon for gardeners in any given area, as it helps them determine which plants do best in their areas and which don't. A plant is considered hardy when it survives the lowest winter temperature in an area without suffering much damage. What this means where the camellia is concerned is that, if you plant one in USDA zone 3b to 4b, where winter temperatures drop to minus 35 degrees F, it will die as soon as the temperature drops below what it normally tolerates in zone 7 to 8, which is no colder than 10 degrees F.