Rarely grown in the West, the Korean thuja is native to a small mountainous area of eastern Manchuria and to northern parts of the Korean peninsula. This slow-growing conical tree can reach over 10m in its native habitat but often remains shrubby in less favourable spots. Due to excessive forest clearance for agriculture, there are few reproductive trees left and the species is on the endangered list in its native area.
Korean thuja has a beautiful regularly conical habit and flattened shoots whose scale-like needles are chalk white on their under-surface. The upper surface is usually a dull dark green but can take on silvery shades in sunny spots. The bark is fibrous, greyish brown in colour.
Korean thuja is the second hardiest of the thuja species which can be grown in Finland. It was first introduced here in the early 1930s when Mustila and the Forestry Research Department obtained seed direct from its natural range.
Two thuja species, the Korean and the Canadian redcedar (T. occidentalis), grow adjacently at Mustila and have produced a hybrid species, a combination of east and west, a rare occurrence on a world scale.