Plant Care 101: Thuja Green Giants

Blair Brown — May 30, 2019

When we say Green Giant, we’re not referring to the Jolly Green Giant, mascot of canned and frozen vegetables. We’re referring to the Thuja Green Giant—and boy, does this massive tree live up to its name.

Quickly reaching heights of 20 to 40 feet tall, the rapid growth of Thuja Green Giants makes them the perfect candidates for large privacy trees. However, even as saplings, Thujas are gorgeous ornamental trees that offer a variety of benefits.

What Are Thuja Green Giants?

Thuja Green Giants are commonly known as arborvitaes, which in Latin means 'tree of life' (their sap has been used for healing purposes). Arborvitae includes all varieties of Thujas, from the Nigra Thuja to the Emerald Green Giant.

The Thuja Green Giant is a cross between two different Thuja varieties: the Standishii and Plicata.

  • The Thuja Standishii is a Thuja variety that’s native to Japan and gets to a mature height of 20 to 35 feet tall.
  • The Thuja Plicata is a variety native to North America that gets to 65 to 70 feet tall.

When these varieties come together, they form the Thuja Green Giant, a beautiful, fast-growing evergreen tree with a pyramidal form. Thuja Green Giants also boast low-maintenance care, strong pest and disease resistance, and a high level of cold hardiness.

Planting Thuja Green Giants

Facts on Thuja Green Giants

Thuja Green Giants are recommended for growing zones 5 through 9. As evergreen trees, they’re cold hardy down to about -20°F, and their strong, durable branches can even handle snow! In fact, you can line your driveway with Thujas, and they’ll create a barrier that helps prevent snow buildup.

The thick emerald foliage on Thuja Green Giants also creates a tough barrier against the wind. Cold, harsh winds can be damaging to smaller trees and shrubs, but mature Green Giants can help protect them. 

And if you need fast-growing privacy trees, then Thuja Green Giants are the way to go. Once planted, these evergreens will grow between 3 and 5 feet a year. People love to plant them to create a living privacy fence, or a natural privacy screen. Thujas can get quite large, up to 40 feet in height and 6 to 12 feet wide, but they respond well to pruning if you want to adjust their size.

Best of all, the Green Giant's exterior evergreen foliage, feathery and light, gives it an attractive texture, while its interior dark green foliage, with slight yellow hues, make it pop. This conifer’s pyramidal shape also looks naturally manicured and attractive to the eye.

Green Giant Arborvitae Care

We've asked our plant experts to answer your most commonly asked questions about Thuja Green Giant care.

How Much Sun Does a Thuja Green Giant Need?

Select a site that receives full sun to partial shade. However, know that your Green Giants will grow more quickly in full sunlight. Six hours of direct sunlight a day will suffice.

What's the best soil for a Thuja Green Giant?

Thujas can adapt to a wide range of soil types, from sandy soil to dirt heavy with clay. Although they prefer slightly acidic soil, they adjust fine to soils that are alkaline and very acidic.

    After planting your Thuja Green Giant, keep the soil moist but not soggy or oversaturated. Thujas won’t do well if they sit in standing water, so avoid low areas of your yard where standing water could collect.

    Why is my Thuja Green Giant turning brown?

    Thujas will turn brown for a couple reasons, most often due to the environment in which they are living. These environmental causes include lack of water, sunlight, and temperatures below -20°F.

    How much water do Thuja Green Giants need?

    These arborvitaes get thirsty often. Water your Thujas three times a month during the summer months, and twice a month during the colder months. If you experience periods of drought or extreme heat, water your trees more often.

    It’s easy to tell when Thujas aren’t getting enough water: their needle tips will start to turn brown or the foliage will look dull, yellowed, and weak. Signs of overwatering include drooping branches and discoloration of the branches.

    What's the best mulch for a Thuja Green Giant?

    You can help your soil retain moisture by placing a 3-inch thick layer of mulch around the tree’s base. The mulch will also keep weeds away and regulate soil temperature. Mulch will keep your soil warm in the winter and cool in the summer.

    Fertilizing Thuja Green Giants

    Generally, Thuja Green Giants don’t need to be fertilized. However, when you plant them, you can help them get established more quickly by adding Root Rocket® Evergreen Rocket.

    To give your Thujas a boost as it grows, you can also add a well-balanced, slow release fertilizer (like formula 10-10-10 or 14-14-14) to the soil once or twice a year. If you choose to fertilize your Thujas, do so in the early spring (after the final frost of the season) and/or in the early fall.

    How to prune a Thuja Green Giant

    No pruning is required for Thuja Green Giants. They’ll quickly reach their massive heights if left untouched. You can promote wider growth that spreads out into a bushier formation by cutting back around a third of the tree’s central leader (the main trunk in the middle of the tree). You can even mold Thujas into hedges that are flat across the top, as long as their width is at least 6 inches. Use hand pruners or shears to cut and shape your Thujas as desired. 

    Evergreen Trees for Privacy

    Thuja Green Giants aren't the only evergreen trees that can create that natural privacy screen. If you're looking to mix it up with another evergreen species or variety, check out our Privacy Tree Collection.

    Blair Brown

    Blair is the Content Marketing Manager at FastGrowingTrees.com, and though she's not your traditional gardener, the planting world is definitely growing on her (pun intended!). She's enjoyed digging into plant care and maintenance and growing her plant collection, especially with exotic indoor varieties.

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