Arborbitae, botanical name is Thuja; family Cupressaceae, constitutes a major group of small to medium (some large) size evergreens used in the landscape. Many cultivars of different form, size, and with varied foliage color are available. Five species in cultivation are native in North America and Eastern Asia. Thuja orientalis (which is more correctly called Platycladus orientalis) is the least hardy of the species and is used extensively in the Southeast, Southwest and West. Some cultivars of T. occidentalis are of good quality, however, many types have a tendency to discolor in the winter, with center foliage browning in the fall.

Arborvitaes are not considered to be of the highest quality because of winter discoloration, loss of foliage, and a thin and ratty appearance with age. Because of this, many types tend to decrease rather than increase in value, especially in congested planting sites. Thuja occidentals cultivars ‘Emerald’ (‘Smaragd’), ‘Nigra’, and ‘Techny’ are very valuable as they maintain good green foliage color in all seasons. The hybrid ‘Green Giant’ has become a popular choice in recent years.

We cover selecting, siting and troubleshooting Arborvitae in detail in our Guide to Arborvitae.

Culture –

Arborvitaes should be planted in fertile, moist, well-drained soils, although in the wild the species may be found on wet and dry soils (maximum growth is not realized on these sites). They are easily transplanted balled-and-burlapped or as container grown plants about any time of year. They perform best in full sun, although light shade is acceptable. In heavy shade plants become loose, open, and lose their dense constitution. Thuja plicata appears more shade tolerant than T. occidentalis or T. orientalis. Pruning can be accomplished prior to growth in the spring and in summer.