How to Choose and Space Arborvitae Trees for a Perfect Hedge

Does your neighbor’s emerald green arborvitae look great – especially when compared to your tired old wood privacy fence? Are you playing with the idea of adding arborvitae trees to your landscape for a windbreak or hedge? With so many different types of arborvitae currently available, you have plenty of options – if you know how to choose wisely. With just a bit of botanical know-how, pick the best cultivars for a great hedge today. Are you ready to get started?

Introducing: Arborvitae Trees

Arborvitaes are actually shrubs, small or even large trees, depending on the cultivars. For example, the Chinese arborvitae (Platycladus orientalis) is a common sight along walkways, where the shrub may be pruned to resemble a small tree of a distinct vase shape. Left alone, it can reach a height of about 15 feet and spread approximately 10 feet. Unfortunately, this particular kind of arborvitae does not take kindly to repeated pruning.

For the gardener who desires a windbreak, divider or hedge, the arborvitae of the cypress family hold more promise. In particular the “Green Giant” cultivar (Thuja standishii x plicata), as outlined by the United States National Arboretum, is a star among hedges. Just like its other family members, it thrives in poor soils, resists disease and makes do with heat, humidity but also dry conditions.

Spacing Tips for an Arborvitae Hedge

Planting a hedge involving any of the cultivars claiming the arborvitae distinction requires the gardener to be mindful of the particular cultivar in question. For example, the Green Giant reaches a height of 60 feet and a spread of 12 to 20 feet. In contrast, the University of Illinois explains that the Holmstrup cultivar only grows up to about 12 feet and spreads over three feet. The Smaragd, another popular cultivar, reaches a height of 15 feet and spreads about four feet, when mature. Plant any of these tree hedges with their adult sizes in mind.

As a general rule of thumb, space the immature trees about four feet apart for cultivars that remain somewhat small; for the giant arborvitae, it is best to anticipate the mature growth and maintain a 12 feet spacing.

Help! There are Holes in my Hedge!

Spacing for an arborvitae hedge is a long-term commitment. Unlike fast-growing lantana that may be trained up a trellis for quicker coverage, these trees will grow to maturity in the course of years or even decades. There are generally two methods that make the needed spaces look less wasteful:

1. Plant a double row. The University of Kentucky suggests spacing the rows about 18 inches apart, but it may be wiser to go with 25 inches or even wider, depending on the size of the cultivar. Plant the arborvitae in an offset pattern, so that a frontal plant covers the space between two posterior trees.
2. Use filler plants until the trees grow in. Annuals, shrubs that transplant easily, and even container plants make for place markers that cosmetically beautify a hedge that looks as though it is full of holes, which truly are the spaces left by the gardener who anticipates the trees’ mature sizes.

A frequently overlooked growth pattern of an arborvitae hedge is the height. The taller cultivars are generally not the kinds of tree hedges to grow beneath power lines. Moreover, be sure to contact the local utility company before breaking ground; plenty of gardeners have made the unpleasant discovery of gas or water pipes while halfway through the planting of a hedge.

Sources

The United States National Arboretum: “A Jolly ‘Green Giant’ Spotted at the National Arboretum

University of Illinois: “Arborvitae”

University of Kentucky: “Guidelines for Choosing Hedges for Kentucky Yards”

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