Arborvitae (Thuja occidentalis) are coniferous evergreen trees in the cypress family. The leaves and bark are high in vitamin C, and the title “arborvitae” means “tree of life” in Latin. The tree is indigenous to North America and is cold hardy to U.S. Department of Agriculture plant hardiness zone 3. There are several characteristics of the arborvitae, also called white cedar, that differentiate it from other conifers.
Size and Shape
Arborvitae are narrow, pyramid-shaped trees which come to a stage on top. They climb about 30 feet tall and 10 feet wide from the home landscape, using a few arborvitae in their natural atmosphere growing up to 60 feet tall. The branches are covered with foliage from the top of the tree into the bottom branches which could grow all of the way to ground level, unless they have been damaged, painted by deer or other insects, or planted where the base of the tree is scaly.
The foliage of the arborvitae grows in flat sprays using miniature scale-like leaves, unlike the outward-growing needles of a number of different conifers. The newly forming leaves are feathery, and they obtain their scale-like look as they age. Foliage is green, sometimes turning yellow during winter months, and the person leaves are far less than 1/8 inch wide. Leaves are arranged along branchlets that develop in flat sprays from the principal branches. When crushed, the leaves emit a distinct odor.
Bark and Cones
The bark of the arborvitae is gray, turning a reddish color as it ages. Furrows from the gray bark show that the reddish color that will eventually be more widespread. The tree creates male and female cones which are just 1/2 inch extended. The cones form at the tips of branches and grow in an upward direction. They start out green and turn brown as they mature. Unlike the open cones of pines, arborvitae cones look like miniature scale-covered eggs.
Location and Pests
In the home landscape, arborvitae are frequently seen growing in rows of closely-planted trees to form privacy screens, windbreaks or boundaries. Small groups of two to five trees are sometimes planted together as an accent in the lawn. In the wild that the trees are generally found growing in wet, low-lying areas. The trees need full sunlight, therefore arborvitae growing in shady areas will likely look scraggly and feeble. A pest commonly associated with arborvitaes is that the bagworm. Bagworm presence is indicated by the hanging pods they produce which may be mistaken for cones, except the forks hang from the branches while the cones grow upward.