Green Giant Arborvitae was a somewhat mysterious hybrid originating at a nursery in Denmark. After a war, intercontinental transit, and some poor record-keeping, a noteworthy tree was finally set aside in the 1960’s as something very special at the National Arboretum in Washington, D.C. The characteristic that really impressed the arboretum staff was its unusually large size and fast growth. Years later, as technology improved, DNA testing on the plant showed that the special seedling was a cross between Western Red Cedar (Thuja plicata – a giant conifer species native to the Pacific Northwestern US with mature heights up to 230’!) with a Japanese Arborvitae (Thuja standishii – native to Japan, mature heights up to 100’). With the speed of the Thuja ‘Green Giant’ growth rate, it appears to demonstrate what is called “hybrid vigor”, making it grow faster and have better pest resistance than either of its parents. Under good conditions, it can grow 3-4’ per year, sometimes even growing 5’ in a year!
So what makes Thuja x Green Giant arborvitae more desirable than a different fast grower, like Leyland Cypress? The wonderful thing about this hedge is that it has fast growth combined with a narrow, upright habit. At 10 years, you could have a tree that is 12’ tall by 4’ wide, without even trimming it.
Some Arborvitae types tend to go off-color in winter months, developing a brown or bronze cast. Green Giant Arborvitae , however, keeps a beautiful bright green color all year long. Evergreens really should be gorgeous in winter, since they are the only things providing color to the landscape!
Thuja Green Giant maintains its bright green color even in winter.
Many arborvitae tend to have problems with diseases and pests, but the hedge has noteworthy resistance to the common issues. It even has some deer resistance, which makes it an improvement over deer-favorite Thuja occidentalis. The main problems you could encounter would be either too little or too much water, or not enough fertilizer. Just give it moderate water, especially right after planting or in hot months, but make sure it is in a well-draining area. Pest problems could include bagworms or scale but these instances are extremely rare due to the vigorous nature of Thuja ‘Green Giant’. Pests tend to attack weak plants, and this variety does not fit that description.
Green Giant Arborvitae is hardy in USDA Zones 5-8, which covers a good portion of the United States. This range can be stretched a bit into Zone 9 regions that are humid in summer. Arid Zone 9 areas will be tough on Thuja ‘Green Giant’ in the summer, but as long as there is ample water it will do fine. This makes it popular in Florida and other southern states.
Green Giant Arborvitae does well in full sun but can also manage in partial shade (at least 6 hours of sun daily).
A Green Giant hedge will thrive in almost any type of soil. If you are planting in an extremely sandy soil with poor nutrients and water-retention, amend your soil with compost generously before planting and apply a thick layer of mulch yearly to help improve the soil’s structure. If planting in a wet area, mound up the ground where you are planting the hedge to provide some better drainage. Areas with prolonged standing water will be difficult for most plants to endure.
As you know, Green Giant grows fast. There is a crucial period in the life of a fast-growing hedge where a strict pruning regimen must be followed, or you could end up with a lanky, thin hedge for the next several decades. The timing, intensity, and frequency of pruning are all important to keep the hedge dense and beautiful, and some of the requirements are counter-intuitive (“If I want my hedge to grow bigger, I should prune it more…wait, what?”)
There is also the issue of spacing. How far apart should you plant Green Giant Arborvitae trees? Generally, the advice is to space Green Giant trees anywhere from 3 feet to 10 feet apart depending on how tall the hedge is desired to grow and how large the plants are to begin with. Clearly this is a wide range of appropriate spacing, and it can be difficult to tell which option is best for a specific project.
With InstantHedge, we take care of that part for you. When you purchase a Green Giant Arborvitae InstantHedge, you are guaranteed a vigorous, healthy, finished hedge from day one. The hedges will arrive pre-shaped and pre-spaced and with a vibrant root system that is ready to grow and establish. Why not start with a hedge that has already been finished by hedge experts? We have multiples sizes of Green Giant Arborvitae for sale.
For more information about Thuja x ‘Green Giant’, please visit the American Conifer Society.