Green Giant or Emerald Green – What is the Difference?

That screen or hedge you plant is an important part of your garden, and something that is going to be with you for many years. Making the right choices, planting it correctly, growing it up, and maintaining it, are all steps along the road to the perfect hedge – beautiful, functional and easy to care for. Hedge plants might all look green, but they are all different, and making the right choice is the first step on the road to that perfect planting. The top two evergreen trees for hedging are certainly Thuja Green Giant, and Emerald Green Arborvitae, so which should you choose? Let’s answer some of the basic questions often asked about these plants, to help you make the right choice for your particular situation.

What is the Difference Between Green Giant and Emerald Green?

Let’s start with how they are the same. Both these trees are evergreen conifers belonging to the group botanists call Thuja. They are part of the cypress family, and a small group, with just five members. All of them are trees of different sizes, and all have scaly green leaves that cling to fan-shaped small branches, creating a dense structure. Older trees develop small cones – which is why they are conifers. They are called cedars, arborvitae, or thujas – all these are the same trees.

Of those 5 species, three are native to North America, and two to Asia. Their connection dates back to the time before the Pacific Ocean pushed those two continents apart. Emerald Green is a form of the Eastern White Cedar, Thuja occidentalis. This tree saved the lives of the early settlers, when native Americans showed them how to make a tea from the foliage that prevented the development of scurvy in the wintertime. Those grateful settlers called it the Tree of Life – which translated into Latin is ‘arbor vitae’ – the origin of that common name.  Although an American tree, it was a Danish nurseryman who found the form he called ‘Smaragd’. That was in 1950, and the great virtue of this plant was that it stayed green all winter, instead of turning bronzy-green they way most of these plants do. That is why grateful American gardeners nicknamed it Emerald Green.

The story of Green Giant is more complex, and also happened in Europe, at the same Danish nursery – D. T. Poulsen. In the 1930s they found a plant that they believed was a hybrid between a Japanese Thuja (Thuja standishii) and a Western Redcedar (Thuja plicata), they had growing near each other. These two plants grow on opposite sides of the Pacific Ocean, so they could only meet when brought together in a garden. Because of world events it was only in the 1960s that a specimen arrived in America, and only in the early 1990s that nurserymen noticed this plant and realize what a great hedging and screening plant it would make. It had never been named, but the name ‘Green Giant’ seemed very appropriate, so that is what it became.

Which One Should I Grow?

Interesting as all that is, the big question for most gardeners is, ‘Which one should I choose?’, so let’s try to answer that question.

Which One Grows Fastest?

On this question there is no doubt. While Emerald Green is certainly a steady grower, adding as much as 12 inches a year once established, under good growing conditions, Green Giant puts that to shame. Like other plants that are hybrids, it is very vigorous, and can grow 3 feet a year when young. Over several years it will add several more feet to its height than Emerald Green will. So if it was simply a matter of growth-rate, Thuja Green Giant is undoubtedly the winner. In fact, there is nothing else that grows so fast, or creates a barrier so quickly.

Which Grows Biggest?

Size does matter – with hedges too. If you are looking for a tall screen or hedge, over 10 feet tall, then you should go with Thuja Green Giant. If left unclipped it will reach 30 in as many years, and it will be 12 feet wide if grown in the open. That is a big plant, so if you are planning not to clip, be sure you have the room for it, and allow enough space for its width too. No point in planning a ‘no trimming’ screen and then having to trim because it has grown all over your driveway!

For smaller hedges, screens and specimen plants, choose Emerald Green Arborvitae, because it only grows 12 to 14 feet tall, and 3 or 4 feet wide.

Where Do They Grow Best?

If you live in the colder parts of the country – zones 2, 3, and 4, the Emerald Green Arborvitae is your obvious choice. It is completely hardy to minus 50 degrees Fahrenheit, without even needing winter protection. Green Giant might survive, with some injury, in zone 4, but beyond that it is ‘no contest’. Colder areas are just not suitable for that plant. Emerald Green will also grow well up to zone 7, so for smaller hedges in areas where you could grow Green Giant, you might decide that Emerald Green is your better choice.

In the warmer zone 6, 7, 8 and even 9, then Green Giant Arborvitae is the obvious choice – and the only one in zones 8 and 9.

Will Deer Eat Them?

It is impossible to be definitive about deer – when they are hungry enough they will eat just about anything. But Green Giant has been found to be deer resistant in many parts of the country, while Emerald Green is much more likely to be eaten. If deer are a problem where you live, the answer is obvious.

What Kind of Soil Do They Like?

Here too there are some clear differences. Both these plants do well in most kinds of soil, but Emerald Green, because it is a form of the eastern white cedar, will grow well even in wet, partly flooded areas, or any soil with poor drainage. If you have wet soil, and are zone 7 or lower, then Emerald Green is the better choice. If the soil is well-drained, then Green Giant Arborvitae will grow well, in anything from sandy soil to clay.

Which Makes the Best Hedge?

The answer here is simple – both. What matters in creating a smooth, flat-fronted hedge – which is what most people like to see – is spacing. Since Emerald Green is only about 4 feet wide when mature, in a single row you need to plant them just 2 or 3 feet apart, otherwise they will never grow together properly. With Green Giant, you can space them 3 to 5 feet apart, and still grow the perfect hedge. That difference means you need fewer plants, and the cost of a hedge will be lower.


So there is the answer – it depends. . . Now you have plenty of information to make your decision – so you are much more likely to make the right one.