Camellia japonica and most of its cultivars are considered to be winter hardy to USDA Zones 7-9. Even where winter hardy, unusually cold temperatures in winter (below 10 degrees F), particularly when occurring as a sudden temperature change, can damage or sometimes kill these plants.
Where winter hardy, Camellia japonica should be grown in moist, acidic (5.5 to 6.5 pH), loose, organically rich, well-drained soils in part shade. Consistent and even moisture is important. Avoid wet soils. Plants require protection from direct afternoon sun and wind. Best location may be sun-dappled part shade. Best with a root mulch.