GROW GUIDE FOR THUJA ‘GREEN GIANT’ ARBORVITAE

Thuja Green Giant tree has become one of the most popular trees for creating a living screen. It’s no wonder: Green Giant is an evergreen plant throughout the year; it is adaptable to most soil types; it is tolerant of light shade and of moderate drought; and it grows extremely fast. Thuja arborvitae has been called the tree of life in latin and was brought to North America to be put in the United States National Arboretum in 1967 from Denmark.

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You may be wondering how fast do arborvitae grow? The thuja green giant arborvitae growth rate puts on 3-5 feet per year of height. A row of rich Green Giants will quickly create a privacy screen that blocks the wind and snow, and blocks the view. The dark green foliage of the green giant plant can grow in a wide range of soils. The green needles may darken to reddish brown or bronze slightly in winter.

Thuja ‘Green Giant’ is a large tree hybrid between the American native, western redcedar (Thuja plicata), and the Asian native, Japanese arborvitae (Thuja standishii). Thuja Green Giant evergreen trees grow faster and are said to stay bright green in winter than either parent. It is more cold hardy than the Japanese species and more tolerant of a lethal fungus (Didymascella thujina) than the American species.

Green Giant Arborvitae Size

The big Green Giant is capable of reaching up to 60 feet tall, with a 15-20 feet wide spread across its bottom at full maturity.

Thujas create excellent privacy between neighboring houses
Because of its fast growth rate, Green Giant is among the best choices for a quick evergreen hedge or screen, privacy fence, or wind and snow break. A row of giant thuja trees along your property line as a screen plant will protect more vulnerable plants and your home from damaging winds.

Line the driveway with a row of emerald green arborvitae plants to create a barrier that keeps drifting ice and snow away. With lower branches that will eventually extend way out beyond the trunk, Green Giant has a tall, imposing narrow pyramidal habit and can sometimes be conical shaped. However, it can be kept compact by regular pruning. In fact, Green Giant responds well to clipping and pruning, even to moderate shearing. The best time to prune thujas is in the early spring.

Planting Arborvitae: Site Selection

Green Giant performs best on moist, fertile, well-drained, loamy soils in full sun to partial shade. It will not survive on varieties of soils that are wet sites, poorly drained, or ones that stay soggy, and it doesn’t like highly compacted soils. Ideal conditions in USDA planting zones 5 and 6, at least 6-8 hours of direct sunlight is best; in warmer climates, a little shade, especially in the afternoon, won’t hurt. Check out our Where Should I Plant Thuja Green Giant blog for more info. As always, perform a soil test if you are unsure.

As a majestic sentinel tree, Green Giant has few equals. A pair of Green Giants on opposing sides of the yard will frame your landscape in grandiose form. In a larger yard or park, position a cluster of three Green Giants for a positively regal focal point.

Thuja Green Giant Arborvitae Spacing

For a living privacy screen or hedge, a windbreak, or a snow break, position Green Giants 5-6 feet apart. Or better yet for a unique green giant hedge, plant them in two rows, 4 feet apart, with the trees staggered 8-15 feet apart within each row. The row(s) should be at least 6-8 feet away from any building, driveway or road. Thuja green giant arborvitae spacing is important so the landscape trees can grow to their maximum potential.

How to Plant Green Giant Arborvitae Tree

If your soil is very compacted, you should consider tilling before digging the individual planting hole(s). You can plant any time of the year, but the best time for planting a new tree is in spring, before it gets too hot, while still allowing a whole growing season before winter to establish a strong root system.
Newly planted green Thujas will need plenty of water the first growing season to establish strong roots.
Before starting, thoroughly water the soil in the nursery pot so that the Green Giant’s roots are fully wetted. Place the pot on its side and slide the root ball out.

If the plant is stuck, you can slip a long-bladed knife around the inside edge to loosen it. Gently loosen some of the roots along the sides and bottom of the root mass, and pull them outward so they are not encircling the root mass. It shouldn’t be necessary to prune any of the roots unless they are wound around the circumference of the pot. In that case the offending roots should be shortened so that when they are in the ground they will grow outward and not continue growing in a circle.

Dig a hole twice as wide and a little deeper than the container the Green Giant arrived in. Do not add any evergreen fertilizer or amendments. Mound up some soil in the middle of the hole, 3-6 inches high, and place the center of the root mass on top of the mound, spreading roots out in all directions around the hole.

Begin filling in the hole. Backfill until the top of the root mass is at the same level it was in the original nursery pot, never lower. You may have to pull the plant up as you backfill. When the hole is half filled, give it a good soaking of water. When the water has drained, readjust the depth of the stem if necessary and finish filling in the hole. Gently tamp the surface of the soil around the root ball down with your hands to ensure there are no air pockets near the plants roots.


Build a 3-6 inch high dike of soil on the surface around the outside of the root zone. This will impound water over the roots as it sinks into the soil. Water your trees thoroughly. Spread an organic mulch 3-6 inches deep over the root zone and beyond to help hold in soil moisture and prevent weed growth. You can use hay, straw, leaves, pine needles, bark or wood chips, grass clippings, or compost. Keep the mulch 3-4 inches out from the trunk. Do not fertilize at this time.

Wondering how often to water thuja green giant?

Water every day or two for the first 2-3 months, until the plants are established. After that, they should get one inch of water every week or ten days. If you’re having a dry spell, or your soil is very sandy, you should water more often with the expandable hose that will come really handy. Once the large trees are established, they are very drought tolerant.

The most common reason for any newly planted tree to die is lack of water.

Your Green Giant shrub will need about an inch of water, either from rainfall or irrigation, per week. Renew the mulch layer as needed to protect the roots from drying out, freezing, or overheating, and to smother weeds. Use an organic mulch that will decompose and add nutrients to the soil. Try to maintain a mulch layer 3-6 inches deep around the tree at all times, but keep it a couple of inches away from the trunk itself.

Green Giant Arborvitae Care

Without any pruning, Thuja ‘Green Giant’ will grow into a stately pyramidal shape with foliage that stays dense all the way to the ground. After its first year of growth, it can be pruned to fit your needs. To maintain a low hedge shape, you will need to shear several times during the growing season.

Thujas are relatively disease free, but check out our Pests and Diseases of Thuja Green Giant blog for more information if you are dealing with issues. They are also deer resistant so you don’t have to worry about those critters eating your trees. One way to know if something is wrong with your thuja is by watching the evergreen needles. If they change color, turn brown, fall off you know that something is wrong.

You simply cannot go wrong with Thuja Green Giant – they are the fastest growing evergreen trees, can provide privacy in as little as a year, and Perfect Plants has many size options to get you the exact tree you need! Want a similar tree that does not get as large?