Arborvitae: Ultimate Care And Growing Guide

Arborvitae Growing Guide: Everything You Need To Know

Arborvitae are very common plants, often found as part of a hedge or border. They are in the genus Thuja, with 2 of the 5 species native to North America. The arborvitae tree may grow multi-stemmed, with a single trunk narrow and straight, or wide with many branches, depending upon the species. They range from dwarf forms to very tall evergreens.The Thuja tree is low maintenance and popular for this reason as well as its evergreen beauty. 

Quick Facts:

Botanical name: Thuja occidentalis

Height: 8-12 feet ( 2.4-3.6 m.)

Spread: 3-4 feet ( .9-1.2 m.)

Sun exposure: Full sun to partial shade

Soil requirements: Moist, well drained loam

Hardiness zones: USDA 2-7

When to plant: Late winter or early spring

Arborvitae Care

When an Arborvitae bush is crowded it tends to remain skinny and narrow. When planted as a single specimen the plant will spread out more. The brown stems branch out to scale-like green leaves. When mature, the Arborvitae bush or tree will develop small, insignificant flowers that look a bit like tiny pine cones. The foliage forms all the way to the ground, making it a perfect screen plant. 

Light

Most species of Arborvitae are very tolerant of a range of lighting conditions. They don’t do well in locations with little to no sun, but thrive in full to partial sun. They will do fine in an area with late afternoon shade, but with more light they produce better foliage growth and color. 

Water

When these plants are first installed they will need to be watered twice per week. After they are established, give the tree or shrub ½-1 inch (1.27-2.54 cm.) per week. The plant can withstand brief periods of drought when mature, but a lack of water will lead to browning of the leaves and overall decline of health. 

Temperature & Humidity

Arborvitae can withstand temperatures between 5-85 degrees Fahrenheit (-15-30 C.). Their preferred range is in the cooler reaches since they are primarily temperate climate plants. Excess heat will cause foliar drop and possibly deformation. 

Soil

If there is anything this stoic plant needs, it is excellent drainage. Many trees are lost when they are installed in a site with heavy clay soil and boggy areas, which results in root rot. Amend heavy soils with organic matter. In severely soggy areas, install drainage pipes or avoid planting Thuja in that site. Most pH ranges are tolerable. 

Fertilizer

The amount any plant is fertilized should depend on available nutrients in the soil. A soil test can confirm any lacking nutrients or minerals. Most Thuja are fertilized in early spring with a formula such as 10-5-5. This is a high nitrogen ratio which fuels leafy, green growth. 

Problems, Pests & Diseases

It is not uncommon to see an Arborvitae hedge with several dead plants. This could be due to overcrowding, overly wet soil, disease, or other issues. Deer are common pests that enjoy browsing on Arborvitae. They have few insect pests except perhaps mites and bagworms. 

When the foliage develops a grayish hue, the problem might be mites. Overly wet soil can cause fungal disease. In areas with heavy snow and freezing rain, the top of the plant can split due to the weight of the snow. Tie up the top to prevent breakage.

How to Plant Arborvitae

After the soil has been amended to provide acceptable drainage, dig a hole twice as wide as the root ball. It should be just deep enough that the top 1 inch (2.54 cm.) sits above the surface of the soil. Spread the roots out gently and backfill, packing soil around the roots. Water the tree thoroughly to settle the soil. 

Pruning Arborvitae

Thuja plants don’t need pruning. If necessary, remove any dead or damaged plant material. In early spring the plant can be lightly pruned on the tips to encourage the natural pyramid shape.

Propagation

It is possible to propagate an arborvitae from cuttings. Take cuttings from a young, new branch in early fall. Make a clean cut at a 45-degree angle. The cutting should be at least 5 inches (12.7 cm) with healthy foliage and a woody cut end. Stick the cut end into damp sand and the cutting will root. 

Repotting

The smaller species of Arborvitae make excellent container plants. They should be repotted every year or so to refresh the soil. Potting soil with a bit of gritty material makes an excellent medium. The container should be several inches ( 5 cm.) wider than the root width and deep enough to give roots room to grow. 

Arborvitae Varieties

There are many cultivars of Arborvitae. American Arborvitae is probably the most common species, with Giant Arborvitae close behind. For yellow colored foliage there are Golden and Twisted Brilliance Arborvitaes. Other varieties are Holmstrup, Japanese, Red Western Cedar, Golden Globe and Emerald. Dwarf forms are Hetz Midget and Baby Giant. 

Frequently Asked Questions

How Fast Do Arborvitae Grow?

Arborvitae are fast growing and can achieve 1-2 feet (.31- .61 m) per year initially. Once mature they will produce up to 9 feet (2.74 m) annually. 

What Is the Downside of Arborvitae?

Although these are very hardy plants with few issues, they do not perform well in hot, dry climates, dry winds or salty conditions. Even with extra irrigation, the trees can suffer.