Will Thuja Green Giant Grow in My Garden?

This is a very common question from gardeners who have read about this fast-growing tree, and want to use it in their garden. It certainly makes a wonderful screen or hedge, as well as being perfect for big specimens to give presence and structure to your garden. This is a very reliable and adaptable plant, but it certainly pays to check if it is ideal for you. There are a few basic parameters of your garden to consider, and then you will know if you can join the millions of happy growers of today’s most popular evergreen.


Across the country there are many different climate zones, usually based on the average winter low temperature. Remember that plants are not affected directly by wind-chill, although cold winds can damage them by desiccation. So ‘real feel’ temperatures are not important, just the actual temperature. The USDA zone system is the most widely used, and you can find out your zone just with your postcode. Thuja Green Giant is hardy all through zone 5, and anywhere warmer until we reach zone 10. If you are in zones 5 to 9, then you have reached first base.


The next thing to consider is rainfall. Take a look at this map, which shows annual average rainfall by state. Ignoring the states that are zones 3 or 4, if you live in a blue state, you can grow Thuja Green Giant very easily. After watering regularly while it becomes established, you will probably only need to water during extended dry periods in summer, which will not even be an annual event. If you have very sandy soil you may need more frequent water.

If you live in a yellow state, you will need to water during most summers, and having a simple irrigation system, especially during the growing phase of your trees, will definitely be an asset. Only if you live in an orange state do you need to think about possible alternatives. For those areas, consider using Italian Cypress, or an upright type of Juniper, for a hedge, unless you are able to provide all-year irrigation.

Soil Type

Because soil is the basis of all your gardening, no matter what you plant, you should always check your type of soil. Thuja Green Giant is very tolerant of many soil conditions, so it will grow in most gardens without problems. Even so, since this is vital information that will guide all your plant choices, check it out – it’s easy to do. Soils vary too much across small distances for their to be national maps to help us.

 Find Your Soil Type

There are three important aspects to soil and they are easy to determine. First is your soil texture. This is how fine or coarse the particles in your soil are, and it tells you if you have sandy soil, clay, or something else. No special tools are needed for this simple job. To begin, scoop up some soil from a few spots in your garden, and mix it together.  Even in winter, if you can scrape back the snow and dig out a little soil, it will soon thaw when you bring it inside. Take a palmful of the mixed soil, and place it in your hand. Add a little water if needed, and mix until the soil no longer sticks to your fingers, but forms a ball.

Squeeze and push the ball of soil out of your palm over your first finger, using your thumb, until it forms a ribbon. Do this until the ribbon breaks under its own weight. If the ribbon is half-an-inch long or less, you have a Sandy Soil. If it is an inch long before it breaks, then you have a Loam Soil. A ribbon that holds together for one and two inches tells you that you have a Clay Loam Soil. If the ribbon is longer than two inches, you have a Clay Soil.

Whatever the soil you have, stroke the ball with your thumb. If it feels gritty, no matter how long a ribbon you were able to make, then you have a sandier version of these three types of soil, perhaps a sandy loam, or a sandy clay. These soils will drain well, which is important, but they will probably also need more frequent watering. The smoother the ball feels, the more clay there is in it.

Thuja Green Giant is very adaptable and will grow well in most types of soil. In sandy soils add lots or organic material when planting, and water more frequently, especially during dry weather. You will probably also need to use a granular or liquid fertilizer to get the maximum growth from your plants. Clay soil is also improved by adding organic material, since it creates open spaces in the soil and so increases the natural drainage. Don’t water clay soil if it seems damp, as it needs those drier periods to draw air into the ground. This is necessary for the development of a healthy root system.

Find the pH of Your Soil

The second important thing to know about your soil is the balance between acid and alkali. This is called the ‘pH’, pronounced as two separate letters. To test this, pick up an inexpensive kit or probe from your local garden center or hardware store. Acid soils have a pH number less than 7, and alkaline ones have a number above 7. A value of 6.5 is the best number to have for most plants.

Unlike many other evergreen trees, Thuja Green Giant does well even in very alkaline soils, with pH values over 7.5 That makes it a valuable plant for areas like that, which can be hard on many other plants.

Check Soil Drainage

The last bit of useful information you need is the speed at which your soil drains. This is also easy to check. Dig a hole a foot in each direction, and a foot deep. Fill the hole with water, and time how long it takes for it to empty. If it takes less than 10 minutes, you have very fast-draining soil. You should add lots of organic material to help it retain water, and mulch regularly as well. If it takes between 10 and 30 minutes to drain, you have the perfect ‘well-drained soil that so many plants – including Thuja Green Giant – just love to grow in. If it takes an hour or more to drain, then you have slow-drainage, and you should plant your new hedge or screen on a raised mound of soil, digging it up from the sides to raise the planting area at least 6 inches above the surrounding ground. If you are putting in a new garden, or developing an old one, you might want to install drainage tile across the property, especially if it takes 3 or 4 hours for that hole to drain. In constantly-wet soil, you should consider a plant like Bald Cypress, or Willow, for a hedge, as these plants thrive in wet conditions that defeat other plants.

Now You Are Set to Go

Once you have all this information, you can easily decide if Thuja Green Giant is the plant for you. If there are issues, then a lot of them can be fixed with good soil preparation before planting. Don’t forget to also check that you have enough room for what will become a large plant, especially if you don’t trim it. Good luck with your planting plans – knowledge is power!

Do I Need to Trim Thuja Green Giant?

Thuja Green Giant is a plant for everyone, and that includes those who don’t like gardening. Many people are willing to prepare the soil, and plant, but after that they just want their plants to take care of themselves, while they turn their attention to other important matters, like family, or golf. If this sounds like you, and you have been considering using Thuja Green Giant for a screening plant, to hide that ugly view and enclose your garden. Maybe you are not sure, because you see so many examples of this plant used for hedges, where the owners trim once, twice, or even more often each year. You don’t want to do that, so how do you decide if it will work, and what are the limitations of not trimming?

Do You Have the Necessary Space?

Because we see this plant trimmed into hedges so often, we can be forgiven for not realizing it is a potentially large plant. Since it is fast growing, it will reach full size in a relatively short time. You can expect a minimum height of ten feet from small plants in no more than 7 years. If you start with plants in the 4 to 5-foot range – a good starting size – then in 7 years they will be 15 feet tall. The original plant, which was grown at the National Arboretum in Washington, was over 30 feet tall just 25 years after being planted as a tiny plant a few inches tall. That 30 feet is usually given as the maximum height, but all evergreens grow just as long as they are alive. They grow more slowly, but you can expect your plants to eventually exceed even 30 feet. If you aren’t going to trim, ask yourself if a screen that tall is too much. Remember that it will throw a long shadow for most of the year, apart from the few months of summer, when the sun is high in the sky. If you plant it to the south of your garden, it will give you a lot of shade – maybe you want that. If you plant it to the north, next to a neighbor, then they may not want your shade on their garden.

How Wide Will Thuja Green Giant Grow?

Consider too that a single plant can become 12 feet wide when mature, so a screen of untrimmed trees will be 12 feet thick. The best advice is to plant your screening row of trees 6 feet inside your property line, unless your neighbor(s) agree that you can plant it closer. That way the trees are always on your property, and there is no danger of disputes. Check too with your city. If you are in town, it is possible that there are height limitations of hedges and screens, and if so you should choose a shorter plant for an un-trimmed screen.

Considering this width, it makes sense to plant your trees 6 to 8 feet apart, so that you will have a solid screen in a few years. If you are planting a specimen, then give it a space at least 15 feet across, so that you can enjoy its mature appearance without it looking crowded. Don’t plant in front of windows. If you have 8 to 10-foot ceilings, then the windows on a third floor will be blocked in time. Don’t plant too close beside a door. You should place the trees 6 feet or more away from the edge of the door opening. Rely on your measurements, even if you think it looks too far away – remember they grow fast! Some people plant ‘by eye’, but unless you are experienced with outside distances, you will probably judge it wrongly, and end up having to trim after all.

Careful measurement is much more important when your goal is to not trim your trees. You may have plenty of room, but getting the position just right is the key to avoiding trimming – make a mistake and don’t allow enough room and you will be up that ladder with the hedge trimmers very soon.

Are There Any Risks to Consider?

If you live in an area where fire is a risk, that is something else to consider. If your trees catch fire, you don’t want them to spread that fire to other trees, or even worse, to your home. In fire-prone areas it is best to plant all taller trees so that their outer edges are at least 30 feet from your home, or outbuildings. If you have a sloping garden, then on the downward slope allow 100 feet, as flames will burn uphill more rapidly. Again, go out and actually measure the distances – don’t risk your property for a few minutes work.

All This Sound Great to Me

If you have thought about all this, and you see no problems fitting plants of this size into your garden, then go ahead. Now you have planted them, after careful measurement and placement, just sit back. Thuja Green Giant grows into a beautiful, dense, upright tree, of charm and character. It is resistant to salt spray, rarely nibbled by deer, and sturdy enough not to be blown down in regular storms, either rain or snow. Even if the branches do get weighed down with ice or snow, when it melts they will spring back up, and the form will be restored.

Remember that an unclipped screen will be more ‘natural’ looking. It will have a looser, informal look, and the top will not be perfectly flat and even. It will look great, it just won’t be a formal hedge. Many people think it is more beautiful when allowed to grow naturally, and whether you plant it as a screen, or as an individual specimen in a lawn, this is the perfect tree for that natural look.

Maybe Just a Little Trimming. . .

There is a good argument to make for doing some trimming while your trees are growing. If you do it right, it does not commit you to a life behind a hedge trimmer, but it will give you better looking plants for life. When a fast-growing plant like Thuja Green Giant is young, it is common for several shoots to compete and give several tall growing points on your trees. Each one will develop into a ‘mini-tree’, and give a more open, wider plant. You can easily produce a more tapered, narrower tree with a little formative trimming.

Here is what to do. Select a tall shoot in the center of the tree and leave it untrimmed. Cut back the tops of all the other shoots so that the tall one is at least 3 feet above the others. On a taller tree, make that 6 feet. As you move towards the outside, cut the stems shorter. Always cut back to an inward-facing shoot if you can, as that will keep the form tighter. You can repeat this process once or twice more as the tree grows. The result will be a lovely, flame-shaped tree with lots of elegance, for almost no work. Never cut back so hard that you leave a bare, leafless branch. It will not re-sprout, and you will have spoiled your tree.

In fact, that last point is the main reason why you need to consider carefully before letting your trees grow untrimmed. Once they are tall, it is hard to make them shorter again, because you can only trim back to areas of green growth. It is easy to grow Thuja Green Giant untrimmed. It just takes a little foresight and planning.

5 Top Hedging Plants for 2018

Looking ahead is always fun, and if you are planning to put in a new hedge in 2018, what are likely to be the most popular plants, and why? Looking back can be a guide to the future, so what plants sold well, and performed well, in the last few years?

The top hedging plants continue to be, depending on where you live, Thuja Green Giant, Emerald Green Arborvitae, Leyland Cypress, American Holly and Italian Cypress. You can see hedges made from many, many other evergreens, both conifers and broadleaf trees, as well as from deciduous trees, with Boxwood being very popular for short hedges. But these are the top five plants, and so let’s take a look at each one, and see if it is a good choice for that new hedge you are planning for the New Year.

5 Top Hedging Plants

  • Emerald Green Arborvitae – top choice for cold regions
  • Thuja Green Giant – top overall choice for most areas
  • Leyland Cypress – still popular, but best in moderate climates
  • American Holly – good for damp and shady sites
  • Italian Cypress – best for hot, dry regions

Emerald Green Arborvitae

This plant, a selected form of Eastern White Cedar (Thuja occidentalis), is by far the biggest seller and top choice in the coldest parts of the country. This dense evergreen is hardy to minus 50 degrees, so wherever you live, it can’t be too cold for this reliable plant. Not as fast growing as some others, it will still put on a couple of feet a year when young, and mature into a lovely, dense hedge that could be 12 feet tall if you need that much height. Because you are probably living in a snowy area if you choose this tree, make sure you taper the sides and round the top – keep it narrow to prevent your hedge collapsing under the weight of snow or freezing rain.

Thuja Green Giant

Proven by science to be the fastest evergreen available, this tree, since its introduction around 2000, but known since the 1930’s, has been a real winner. It is a hybrid, and so very vigorous and capable of growing 3 to 4 feet a year. With that growth rate you will have a sturdy, tall hedge in just a few years. It is hardy right through zone 5 and warmer. If you live in most parts of the country, as long as you have moderate rainfall, and don’t get any colder than minus 20, you cannot pass by this plant easily. No wonder it’s the fastest seller in most garden centers. One great advantage over Emerald Green Arborvitae is how green it remains all winter. No bronzing or browning, so your hedges will always look perfect in winter – exactly when we notice them most. Choose it for any hedge over 8 feet tall. Although it is fast-growing, it will slow with maturity, so if you trim just once or twice a year it will always look great.

Leyland Cypress

This hybrid tree has been a reliable standby for half-a-century or more. Not quite as fast-growing as Thuja Green Giant, it is still capable of very rapid growth, especially if fed and watered well. It definitely grows best in moderate climates – not too hot and not too cold, and although fairly drought resistant it will do best with a good supply of water. In hot, humid areas it tends to suffer from disease, but in temperate climates it will do well. One area where they are especially valuable is on the coast. One of the parents is the Monterey Cypress, which grows hanging out over the Pacific Ocean. So if you need a hedge or screen at the coast, look no further than this reliable evergreen for salt resistance.

Remember that Leyland Cypress will grow very large. This makes it excellent for tall barriers, to block out noise or salt-spray. Don’t plant in restricted spaces – a 40 to 60-foot tree that can be 25 feet across has no place in a small yard. Because it has sometimes been planted in unsuitable places, causing problems for neighbors as well as home-owners themselves, this plant has got a reputation as a ‘bad boy’. Don’t be put off if you have plenty of room and need a big screen, this tough, reliable tree is a top choice.

American Holly

Not everyone has a bright, well-drained sunny garden. Shade from trees, and low-lying areas are not top choices for planting most evergreens. If you need a sturdy hedge, but your soil is often damp, and trees throw shade across the area, consider using the American Holly, or other holly varieties. This are broad-leaf evergreens, with glossy leaves of a rich, deep green. Many produce bright red berries in fall and winter as well, brightening the garden at a dark time. They clip well, and grow tough and dense. The spiny leaves will protect your garden from all kinds of intruders too, so you will be safe and snug behind a holly hedge.

American Holly will grow a little more slowly, probably one or two feet a year, but it’s a great choice for any shady, damp areas. If you love the look – and who wouldn’t? – it is also reliable in sun and even in areas that have season drought, once established. So it’s a good all-round choice too.

Italian Cypress

Everyone has seen those pictures of Italy or Provence, with dark, narrow green fingers pointing towards the blue sky. This is the Italian Cypress tree, an evergreen that thrives in zones 7 to 11. It is especially useful in the south-west, where the weather is hot and dry, like its Mediterranean home. Easily the most drought-resistant of all the evergreens, the Italian Cypress clips into a solid wall of rich dark-green you will love. The dark coloring gives a touch of real class, and is cool on the eyes when the sun is blazing down.

Make Your Choice

By now you should have a much better picture of which evergreen will be an appropriate choice for your new hedge. Make sure you prepare the ground well, and give your new trees, whatever choice you make, regular water through their first growing season. Trim lightly right from the beginning, to build a sturdy, dense structure, and you are well on your way to a healthy hedge you can be proud of.