The Beginner’s Guide to Evergreen Hedges and Screens

A hedge that is green all year is the perfect backdrop to any garden – heck, many gardens are simply a hedge, lawn and shade tree, and they provide everything needed to enjoy a simple garden. So planting a row of evergreens to create a clipped hedge, or a less formal, unclipped screen, is often the first major project in a new garden, followed by that lawn and shade tree. Of course, for a more beautiful garden flowering shrubs and other plants are needed too, but without that hedge, many gardens don’t look right. This is especially true if you have an unsightly view, or you are overlooked by a road or near-by houses, and the privacy you achieve from a hedge makes such a difference that most people choose to make it an early priority.

If you are new to gardening – perhaps this is your first home, after living in apartments – then there are plenty of pitfalls, so getting a clearer understanding of what you need, and what is involved, is the first step to take. Let’s do that here, and see what the vital questions are that will guide you through the process.

Questions to Ask When Planning an Evergreen Hedge

  • How high do I need my hedge to be?
  • What plants are the best choice for my area?
  • How many plants do I need?
  • How long will it take to grow?

Let’s take each of these questions in turn and give some answers.

How high do I need my hedge to be?

This is an important question, because you want the plant you choose to do the job, but equally, you don’t want to plant something too big, that is likely to take over in a few years, or throw so much shade your garden suffers.

It is often not obvious how tall a hedge or screen needs to be, unless you are planting right up against a fence or wall you want to hide. Then you can simply measure the height of the wall or fence, and you know the height of the hedge you need. But when it comes to concealing the view of something further away, it gets more complex. There is a simple way to do it though, and here it is. Collect together an assistant, some bamboo canes or tall poles, some string, and a piece of red cloth. Tie the red cloth to the end of one of the canes, and have your assistant hold it on the line where you want to plant your hedge. Stand in the places you want to be shielded from view in and look at that red cloth. Is it high enough? Thought not. Now tie a second cane to the bottom of the first one and try again. Tall enough now? Too tall? Keep adding canes, holding them vertically upright, and checking what it hides, until you are satisfied with the result. Take a measure and see what the height of those sticks are. I bet it isn’t at all what you expected. Now you know the minimum height you need for your hedge or screen. That was simple, wasn’t it!

Knowing the height, you can now choose a suitable plant. For a screen you want something that will reach that height in under 10 years, although if you need a lot of height that could be unrealistic. So something that will grow fast is needed if the height is over 10 feet. Look at the maximum height listed for plants you are interested in and make sure it will even grow to the height you want. Since most plants slow down as they approach mature height, for coverage in a reasonable time you need to choose something with a mature height twice the minimum height you need for screening – or you will be waiting 30 years for your screen. You might need to have the screen topped every couple of years, if excess height is a problem.

What plants are the best choice for my area?

Check your postcode against the USDA zone system, and see where you fall. If you are between Zone 5 to 9, then Thuja Green Giant is probably your best bet. It’s fast-growing, and tough as they come. In colder areas Emerald Green Arborvitae, which is equivalent to a cold-hardy, smaller form of Thuja Green Giant, is the top choice. It does grow more slowly (although still fast) and only reaches 12 feet in height, but that is plenty for a hedge or shorter screen, and most importantly it will live happily even in Zone 3 For a taller barrier, consider using spruce. Both blue spruce and Norway spruce are hardy to zones 2 or 3, and if you use a columnar form you will get height to 25 or 30 feet in time, without a lot of spread taking over your garden.

For hot and dry areas in zones 7 or more, the Italian Cypress is the top choice – it’s incredibly heat and drought resistant. The most awkward weather conditions are dry and cold too, but there Spartan Juniper of Blue Spruce are the top two choices for hedges and screens.

How many plants do I need?

This is easy. Measure the space you want to fill. The basic rule for hedges is one-quarter of the mature width, so it depends on that. Don’t just guess, check it out. Thuja Green Giant, for example, has a mature width of 12 feet, so 3 feet apart is the minimum spacing for a hedge – you can add another foot if you are a little more patient. For a screen you can increase this to half the minimum width, so that is 6 feet for Thuja Green Giant, or up to 8 feet if you aren’t in a big hurry. You can read more details on spacing in this recent blog, ‘Proper Spacing is the Key to Successful Hedges and Screens’.

How long will it take to grow?

This is the most common question, but also the hardest to answer. Thuja Green Giant will add 3 feet a year when young, dropping to about half that after 5 or 6 years. Other evergreens are slower, with 2 feet a year when young being a realistic expectation. Thorough soil preparation, correct planting, watering as needed, and a good fertilizer program will all help you to maximize growth, not just in height, but in thickness and density, which are just as important when it comes to screening and hedges. Light trimming will also help to build a thicker, denser hedge more quickly, so don’t wait until it reaches full size before getting out the trimmers.


If you sort out these questions first, you will be able to make better choices, and have more success with your new screen or hedge. Before you know it you will have that coveted privacy you are looking for.


Thuja Green Giant – How Fast Does It Really Grow?

Here we have the most common question about this tree, and the one where fact and fiction have become twisted together on that most confusing source of knowledge – the internet. Let’s try to untangle that information and get closer to a factual understanding of how fast (and large) it might grow for you, in your location, without the hype, and using some real research to reach our conclusions.

Thuja Green Giant is the most popular evergreen for screening, hedges or specimens in all but the coldest areas of the country, and the hottest and driest. It is hardy from zone 5 to zone 9, which covers most of the country. Its dense evergreen foliage in a rich green color is the perfect backdrop for a garden, and its dense foliage protects your garden from noise and wind. It is also easily grown in most soils, and its toughness, disease and pest resistance, and resistance to deer too, makes it an easy, low-maintenance plant too. Newly planted trees need attention to watering until they become established, but after that Thuja Green Giant will largely take care of itself. It is naturally dense, so it develops into a solid screen even if you never trim it. It also trims easily of course, and it is easy to make beautiful hedges with this tree.

The Growth Rate of Thuja Green Giant

One of the big selling points of Thuja Green Giant is its growth rate. Among evergreens it is probably the fastest grower available, and that ability, and its overall toughness, comes from its hybrid origins. It is a cross between two different Arborvitae species, Japanese Thuja (Thuja standishii) and Western Redcedar (Thuja plicata). This cross was made in Denmark in the 1930s, but it was only after a plant was given to the National Arboretum in Washington that it drew any attention, and only in the 1990s that it became widely available. Since then it has shot to the top in popularity among gardeners. Hybrid plants are usually tougher and more vigorous than either of their parents, and Thuja Green Giant is no exception to that rule. This is why it has a remarkable growth rate. So how fast can it grow? Under average conditions young plants can add 3 and even 4 feet of height each year. Under ideal environmental and climatic conditions it is certainly possible to exceed this, and rates of 5 feet, or perhaps even more, are possible. But for most garden conditions across most of the country, 3 to 4 feet is something you can comfortable expect to see during the early years. We will look later at the different factors that have to be considered to arrive at a realistic estimate in any particular situation, but first, let’s look at some real research that is proven, not just a guess from someone wanting to sell ‘fast-growing trees’.

Back in 1999 the Commercial Horticulture Department of the University of Arkansas established a unique Plant Evaluation Program. Unlike other similar programs using just one site, three sites were established across the state, in three climate zones – zone 6b, 7a and 8a. These allow for comparisons in different climates, assessing both winter hardiness and heat resistance. In 2001 small plants of Thuja Green Giant in 1-gallon pots, were planted at these sites. The trees were planted in full sun, with initial fertilizer and drip irrigation. They were spaced 10 feet apart, and no pest-control or trimming was carried out. Each year the plants were measured, and records kept for 5 years.

The results for Thuja Green Giant were remarkable. At the end of the 5-year period those small plants had an average height just short of 10 feet, and a width of 5 ½ feet. The trees in the warmest location (8a) were 11 ½ feet tall! Even at the coldest (6b) and windiest site they were almost 10 feet tall. The slowest growth was at the zone 7a site, possible due to a period of very wet weather one spring, causing root problems. The years with the fastest growth rate were the second, third, and fourth years, with the plants in the warmest site adding a full 5 feet in their third year alone! The developers of the program (Dr. James Robbins and Dr. Jon Lindstrom) highly recommended Thuja Green Giant as a hedge or screening plant, and it was the fastest-growing evergreen in the trial. See the results here for more details.

What Affects the Growth Rate of Thuja Green Giant?

This careful scientific work tells us that under average conditions Thuja Green Giant will increase its height by 3 to 5 feet in each year. It also sheds some light on the factors that influence that growth, and we also have some other general ways of deciding exactly how much growth to expect.


Notice how in the Arkansas research the trees grew tallest in the warmest zone. This might seem like ‘common sense’, but it relates more to the length of the growing season than other factors such as winter lows (which are the basis of the USDA zoning system). We see the effect of a longer growing season in many plants. Grasses from warm climates bloom in zone 6 and not in zone 4 because they have more time to develop their blooms, not because it is colder in zone 4 in winter. This is an important distinction, because within a single zone factors such as sun exposure and wind affect the length of the season. Most hardy plants like Thuja Green Giant will not grow below temperatures of 45 to 50 degrees. The higher the total number of days the temperature is above that, the more growth. A shady, windy garden will have fewer days above 50, even in the same zone. As well, steady winds make all plants grow shorter, and in an exposed site you will not get as much height as in a sheltered spot.


Every year is different, and weather patterns each year are important. You could be unlucky, and encounter a cold, wet summer the year you plant, or the following year. You will not get the same level of growth from your newly-planted Thuja Green Giant if that happens. If, on the other hand, you have an early spring, and many warm, calm days, growth will be greater. As noted in the research, a wet spring seriously slowed the growth at one site, resulting in much shorter plants after 5 years.

Soil and Water

Some soils are fertile, while others are sand or gravel, with low fertility. These soils cannot support the maximum rapid growth a ‘rich, well-drained loam’ (ever gardener’s dream soil) can do. Poorly drained soils will also slow growth, although a steady supply of enough water is necessary to maximize growth. The north-west, where one parent comes from, and Japan, home of the other one, are places with warm but rainy summers, and mild winters. The growing season is long, and Thuja Green Giant is adapted to the typical soils of those areas. So, in America, the north-west is probably the area where the greatest growth – perhaps that elusive 5 feet a year, is most likely to happen. If you live in the dry south-west, even though you have lots of sun and heat, you will not see such a high growth rate.

So What’s the Answer?

We can see from all this that absolute statements about the growth you can expect from Thuja Green Giant are impossible. Is this a fast-growing tree? Definitely yes. What does that mean in your particular garden? You be the judge. What is your zone? What is your soil like? Will you feed and water regularly? How sunny is the place you are planting in? How sheltered is it? What is your soil like? These are just the most important questions you need to ask, but combining it with the data above, you should be able to come to a realistic conclusion for your own garden.

Proper Spacing is the Key to Successful Hedges and Screens

Planting a hedge or screen is an investment – not just in money, but in time and effort. You wouldn’t make a financial investment without planning, and the same goes for planting too. While there are other important things, like soil preparation, correct planting techniques, after-care and good trimming, all of these count for nothing if the basic step of spacing has been neglected. Plant too close and your hedge will become thin at the bottom, with plants dying out as the strongest win in a battle for survival. Plant too far apart and you will first be waiting for ever for it to fill in, and always have an uneven face, with ins and outs, instead of that perfect flat surface that is the sign of a good hedge. So let’s consider how to space your plants correctly, thinking especially of that most popular evergreen of all for hedges and screens – Thuja Green Giant.

Basic Hedge Spacing Rules

For tight hedges – one-quarter of the mature width of your trees

For screening – a little more than half the mature width of your trees

For extra-solid screening – plant a staggered double row

In poor, drought-prone soil – reduce spacing by 25%

Remember to add room for the width too.

Spacing for formal, clipped hedges

Hedges are based on planting close, so that the trees grow together into a continuous mass. But you have to be careful. Sometimes it is recommended to plant root-ball to root-ball, that is, to pack the plants into a trench with the roots touching. Not only does this take a lot of plants, it results in a poor hedge. It does push the plants into growing tall, so you get the height you want quickly. This is probably where the idea came from, and for a few years it can look great, with a nice dense hedge. But after a few more years you will start to see problems. First, some plants will die, as the ones that were a bit more vigorous to start with begin to take over. You will suddenly see plants turning brown, and the foliage falling to the ground. Once they become bare you need to remove them, leaving gaps in your hedge – never what you wanted! Over time the spaces may fill in from the surrounding plants, but until that happens you have a really ugly hedge.

Even if you don’t get gaps, pretty soon the lower parts of the hedge stop growing, and it thins out just where you want it to be thick and green. Eventually the lowest branches begin to die, and your hedge loses that ‘green to the ground’ look that is so desirable.

Much better is to allow enough room for each plant to develop, while keeping them close enough that in a few years they merge into a solid wall. How close is that? If of course varies with the plant you are using. As a rule-of-thumb, check out the mature width of the plant. Taking Thuja Green Giant as an example, the mature width is 12 feet. So take 25-35% of that, and we have 3 or 4 feet. That is the ideal spacing. It’s that simple. The closer spacing will give you a solid hedge sooner, and the wider spacing will save you money by reducing the number of trees you need, but take a little longer to look full.

Spacing for informal rarely-clipped screens

The basic difference between a hedge and a screen is how often you clip it. Screening plants are rarely clipped, or not clipped at all. You might give them a trim or two as they develop, to build denser structure, and then a ‘touch up’ every few years, but that is about it. A hedge is going to be clipped at least once a year, and usually two or even three times, depending on how neat you are, and how much time you have. Especially in warmer areas, plants have a long growing season, so they will need more trimming.

With a screen, we want the plants to grow out naturally until they touch, so in theory we could plant at the same distance as their mature width, but that will take too long, so we usually go closer. Don’t go too close, as the plants will be pushed to grow tall, but stay thinner, which is a recipe for structural weakness as the screen gets taller. So half the mature width is a minimum, which in the case of Thuja Green Giant is around 6 feet. Again, if you are in a hurry you could reduce that to 5 feet, but don’t go any closer. You could stretch it to 8 or even 10 feet to reduce the cost, but if you need a visual barrier that will take a while at such a wide spacing.

A double row makes a denser screen

If you have plenty of room available, and you want a really solid barrier – perhaps for sound protection for example, then a double row is the way to go. This can be done for a hedge or a screen, and the method is to plant in two rows, at a wider spacing, with each plant staggered, so that the plants in one row sit in the spaces between the plants of the other row.  Even though the spacing is increased, this method does take more plants, but if a really solid barrier is your goal, then double rows are the way to go. For Thuja Green Giant, space the rows 3 feet apart for a clipped hedge, and 5 feet apart for an informal screen. In each row, a wider spacing of between 5 and 8 feet is good for a hedge, and 8 to 12 feet for a screen.

Planting double rows properly requires careful measuring and lay-out, otherwise you will lose the staggered effect. Careful layout is always needed really – that hedge or screen will be there a long time, and any spacing irregularities will glare at you for years to come!

My soil is very poor, and often dry

It is worth making allowances for poor soil conditions too. Rocky or sandy soil, especially if it is often dry, will reduce the growth of any plant, so you need to compensate for that by planting tighter. Reducing all the above spacings by 20 – 25% will do it, and give you something solid, even under poor conditions.

Don’t forget the width

A common mistake of inexperienced gardeners is to plant a screen or hedge right on the property line, or in a space too narrow for the plants. If your hedge impinges on neighboring property, they can cut it right back to the property line, so plant well inside it. Plant 6 feet inside for a large plant like Thuja Green Giant, or a little less for something narrower. That way all the plant will be on your property, and under your protection.

Similarly, when planning a hedge, especially along a path or driveway, set the back by 3 feet for a hedge and 5 feet for a screen, when using a large plant like Thuja Green Giant. Smaller plants will need a little less, but you don’t want your path to disappear in a few years – working with small plants can be deceptive, so do plenty of measuring!

Caring for Older Thuja Green Giant Plantings

A lot of the focus with caring for Thuja Green Giant is on the actual planting and establishment of new plants. This is important, because good establishment means durable plantings and a long life for your bushes. But after a few years your hedge, screen or specimen plants will be established in your garden, and questions come up about caring for these older plants. So in this blog we are going to focus on that – what special care and steps are best for older plants, particularly so that they go on to have a long, healthy life, and continue to play their vital role in your garden for years and decades to come.


It is obvious that newly-planted bushes need extra water until they settle in and send out their roots into the surrounding earth. But how long should this go on? What should we do for established plants if a long drought period arrives?

You should continue with watering new plantings throughout their first growing season. So if you planted in spring or early summer, it is best to water deeply once a week until the cold weather arrives, and winter rain or snow takes over. In the following year you should only need to water if there is a drought of three weeks, but if you have very sandy soil it pays to water regularly – perhaps every two weeks, for that second season. In later years you only need to think about watering if there has been no rain for a least a month, and in many soils your Thuja Green Giant plants will be unaffected by drought periods much longer than that.

The critical season for watering established plants is spring, not summer. Spring is when the major growth push takes place, and that is when the plants need plenty of water. So a spring drought can be damaging – although probably not fata – even to established plants. The new growth will be reduced, it will be thinner and not so green, and repeated over several years, the result will be a thinner plant. So if the weather turns dry in spring, as it so often can, a thorough soaking of your established plants will make sure they perform at their peak best.

Mulching also helps, and with hedges and screens leaving at least some of the clippings under the hedge is the easiest way to create a natural mulch for your plants. That layer of dead leaves will conserve moisture by reducing evaporation from the soil surface, as well as inhibiting weed growth. If you keep your hedge green right to the ground, then those clippings won’t show, and you save time by just blowing or brushing them underneath, instead of having to collect them up.


Young plants always perform best with a regular fertilizer program, but after a few years it can become less important. If your natural soil is a loam or clay soil, it will almost certainly have good natural levels of plant nutrients, and most plants will grow well in it without any assistance. If you have a sandier soil this is not true, and if that sounds like your soil situation, a fertilizer program should be kept up indefinitely. For established plants granular fertilizers, and slow-release fertilizer are best. These require fewer applications a year, and slow-release forms usually need just one spring application, saving you a lot of gardening time. Compare that to liquid fertilizers, which need applying every two to four weeks throughout the growing season – this can become a real chore, especially over the years.

It is usually best to keep up annual fertilizer application even if you have good soil, when growing a hedge of Thuja Green Giant. Trimming removes nutrients that would naturally be re-cycled within the plant, so these need to be replaced for optimum growth. This is also another good reason to spread your clippings underneath your hedge, rather than throwing them away, as their gradual decay will eventually return the nutrients in them to the roots. Evergreen clippings are generally not good in a compost heap, so leaving them in place is the best and easiest way to dispose of them.

In summary, keep fertilizing your evergreens indefinitely if you trim them more than once a year or more, and in all situations if your soil is sandy. For plants left to grow naturally, keeping up fertilizer application is less important on most soils.


If you have Thuja Green Giant, you probably decided when planting if you were going to trim them or not. Some people do underestimate the final size of this big plant, and trimming can become a necessity. If you suddenly see that your plants are too big, don’t rush out and cut them back hard. Like most evergreens, you cannot cut a branch back below where it has green shoots, and have it sprout back. If you get carried away and trim too hard you may destroy your hedge. If it really has become way too big, take back as much as you can, being sure to leave some green growth on every branch. After a year or so it will thicken up, and you can usually go back and get it even smaller than the first time. Better to take your time than destroy those old, established plants.

Even better is to anticipate a plant that is about to become too big, and trim it before, not after, that happens. It is much easier that way, and you will never have to trim so hard that your plants look bad for months, before filling out again.

With a hedge you should have trimmed regularly from an early age, but as your hedge matures it pays to anticipate problems. Keep those sides sloping inwards a little, so that the lower part stays green and thick, and if you live in an area with snow or ice storms, round off the top, keeping it as thin as you can, or the accumulation of ice and snow will break the top and open your hedge out. Watch for sections that seem to be yellowing, as branches can sometimes die back naturally. If you see this beginning, trim back those weak areas while they are still green, so that the surrounding foliage can spread into them. That way, if and when the weak branch dies completely, you will have a much smaller gap to fill in, and you will avoid the eye-sore of a gaping hole for several years. Sometimes too, trimming back an area that is weak will rejuvenate it.

Thuja Green Giant will live for many years, stretching into decades, and it can be maintained as a screen or hedge more or less indefinitely. The secret is to adjust your care techniques as they age, so you avoid problems down the road.

Thuja Green Giant for Screening

Screening is often high on the list of garden projects for many people, especially if you live in a built-up area. Evergreen screening is an effective and low-cost way to screen out unwanted noise, an ugly view, or neighbors, especially if you need screening above 6 feet. Tall fences are expensive, difficult to erect, and are often prohibited by city by-laws, but planting is not. You can put in screening plants that will grow pretty much as tall as you want, and a popular choice for that is Thuja Green Giant. There are lots of good reasons for this – perhaps the most obvious is the rate of growth – so let’s consider this choice in more detail, to see if it’s the right one for you.

Do You Have Enough Room?

Thuja Green Giant will grow, if unclipped, to a height of about 30 feet, and while that might take 30 years, it will be half that height in as little as 10 or 12 years. The bigger trees get, especially in a long screen, the more difficult and expensive it is to trim them, so the first thing to think about is the effect of planting a green wall, 20 feet or more in height? What about light into your home and garden? That will depend a lot on how close to your home the screen is going to be, and of course whether it is to the north or south, or some other compass position. Tall plantings to the north side will not cast a shadow, while in other positions it will. Consider too that the shadow will be longest in winter, because the sun is lower in the sky, and that may be just when you want that extra light.

Remember too that Thuja Green Giant will be up to 12 feet wide in time, again if left untrimmed, so consider how much ground space that is going to take up. Depending on your particular situation you could trim up the lower several feet, as they grow, creating trunks on your screen, which will free up ground-level space, but even then you should plant 6 feet or more from your property line, so that the trees are actually ‘yours’ completely.

For many medium to large-sized gardens, that kind of space is not an issue, but in a smaller garden you might want to consider something smaller, such as Emerald Green Arborvitae, which only grows to about 12 feet tall. It is hardy all the way from zone 2 to zone 7, making it the perfect choice for a smaller screen in colder areas.

How Fast Will They Grow?

Here we get into the reason for the enormous popularity of Thuja Green Giant – its growth rate. Young plants can add 3 feet a year – and even more sometimes. As they mature the growth does slow down, but still exceeds a foot a year. This can be seen with the original planting, where a plant at the National Arboretum in Washington reached 30 feet in 25 years. Tiny plants have been proven in trials to reach 10 feet in 7 years, faster than any other evergreen around.

Good soil preparation and a regular fertilizer program will give your plants the best start and the quickest growth rate, so go that extra distance and reap the rewards.

How Far Apart should I Plant?

Given how big Thuja Green Giant gets, you don’t need a lot of plants to make a screen. Depending on how quickly you want that screen to develop fully, you should plant 5 feet apart for a quick screen, and as much as 10 feet apart for something less solid, that will give the effect of screening without making a solid wall of green. If you do want solid, and you have enough room, then plant a double row. Allow 5 feet between the rows, and plant 8 feet apart in each row for a quicker screen, or up to 12 feet apart for something looser. Stagger the planting in each row, so that one plant stands in the middle of the gap in the other row, creating a tight zig-zag.

What About After-care?

Since Thuja Green Giant is not eaten by deer – at least not usually – and has no significant pests or diseases, there is nothing to do in that direction. The most important care is watering during the first growing season, which should be once a week. Don’t rely on showers or thunderstorms, as most of that water only wets the top inch or two in summer. Instead go for a deep soak from a gently-running hose on each plant, or by installing trickle pipe along the line. It’s important to keep the soil further away from each tree moist too, because you want to encourage the roots to grow outwards into a large volume of soil. That will happen much more if the ground around is temptingly moist, rather than dry.

After that vital first year you don’t need to give so much attention to your trees. Watch for dry periods in the second and third years and give those deep soaks again if the soil is dry below the top few inches. A quick dig around with a spade will show you that – just turn up a few inches of soil and feel for moisture. Increased watering during the early years will also accelerate growth, especially if combined with a fertilizer program.

In the early years liquid fertilizer is best – it gets straight to the roots and is taken up quickly. Feed each month for the best results, and that can be a little time-consuming, so after two or three years switch to slow-release granular fertilizers that only need one application a year, in spring. Choose a blend suitable for evergreens and look for Iron and Magnesium in the added micronutrients listed on the label. They will keep your screen a rich green color all year round.

Should I Trim?

Thuja Green Giant produces a dense plant without trimming, but as the early growth is fast and so more open, a light trim each year while the plants are small enough to reach will make it thicker much more quickly. You only need to take off an inch or two, so it has no real effect on the size or rate of growth, but it certainly makes for a dense screen early on.


Thuja Green Giant is the number one choice across much of the country, and it is probably the best choice for you too, but it pays to think it through first. Hopefully these notes will help you reach the right decision.

10 Top Tips on Trimming Evergreen Hedges

Hedge trimming season is well underway across the country, and after the rush of spring growth, if you haven’t trimmed your hedges yet, or if you did it a while back, now is the perfect time to do it. There is no doubt that the best way to have good hedges is to trim regularly, and the more you cut, the denser your hedges become. Everyone loves the look of freshly-trimmed hedges, so here are some tips on how to achieve that perfect look and keep your hedges healthy too.

  • Keep your trimmers sharp – sharp tools give a clean trim
  • Choose the right tools for the job – your trimmers should match the scale of the job
  • Trim regularly – little and often to develop a strong branching structure
  • Cut in all directions – branches should be horizontal, not run upwards for several feet
  • Slope the sides inwards – the bottom needs light to stay green and thick
  • Start trimming early – trimming a new hedge right from the start is the way to go
  • Never cut below the foliage – many evergreens can’t sprout from bare wood
  • Have a fertilizer program – hedges need regular feeding to keep growing strongly
  • Water before trimming – don’t trim a hedge during a drought without watering first
  • Stay safe – your personal safety with tools and ladders is always your top priority

Keep your trimmers sharp

That look of a smooth, green hedge is the result of clean cuts to the foliage. Ragged cuts turn brown, so your whole hedge looks brown and dull. Blunt trimmers – hand or power – are the most common cause of poor results, and they also slow you down, meaning multiple passes are needed, where a sharp trimmer would cut in one go. Although it’s possible to sharpen them yourself, most of us choose to have a professional do it. Have your trimmers sharpened before the first cut of the season, and if you have a lot of trimming, or do it frequently, you might need a second sharpen in the middle of the season.

Choose the right tools for the job

Trimmers come in many sizes, and the most common error is using a short bar for a large hedge. A long bar not only speeds up trimming, it makes it so much easier to achieve a flat surface. As well, decide what power-source to us. There is a big move today towards cordless electric, and with the new, lighter, quick-charging batteries, it makes a lot of sense. Freed from the hanging cord, and not surrounded by gasoline fumes, trimming becomes a much more pleasant experience. The result? You are more likely to trim more frequently, with improved results.

Trim regularly

The more often you trim, the denser and more durable your hedge will be. This is especially important with a young hedge – more on this later – but even for a mature hedge trimming twice a year, rather than the more common annual trim, makes an enormous difference. Three trims per year will really give you that top-quality look, if you can find the time.

Cut in all directions

The biggest mistake of a beginner when trimming their hedges is to run the trimmer in just one direction – usually upwards. This seems to be ‘natural’, but it causes long-term problems. You end up with a hedge that consists of long, upright branches, with foliage on the outside only. These easily break under snow or in strong winds, leaving big gaps that are hard to fill. A much better technique is to trim in all directions from day one. Upwards, downwards, and sideways too. By doing this you build a hedge with many more-or-less horizontal branches, with dense, twiggy ends that make the face of the hedge. They can’t be dislodged from the hedge, so it is so much stronger, and if one dies, it only leaves a small hole, that rapidly fills in from the surrounding branches.

Slope the sides inwards

To keep the lower part of your hedge healthy and green, it needs light, and it needs reduced competition from higher up. So your hedge should always be wider at the bottom than the top. Light reaches right down, and the bottom gets its share of food and nutrients. If you let the top grow fat the bottom will soon die, leaving you with a hedge that is full of gaps just where you see it most.

Start trimming early

A lot of people wait until their new hedge plants reach the final size they have in mind – 8 feet tall for example, and only then begin to trim.  If you do this you will always have a thin hedge, because there will be too few branches available to make that solid face. So begin early – as soon as you start to see new growth after planting – and trim an inch or two from the top and upper sides regularly. Don’t be afraid this will slow down growth significantly. It won’t, and your hedge will be so much better for it.

Never cut below the foliage

Another good reason to trim regularly is because hard cutting of most conifer evergreens doesn’t work. If you trim a branch below the point where it has green foliage, it won’t re-sprout at all and that branch will never grow again. Some plants are an exception to this, particularly yew trees, which will come back happily even from thick branches. But for cedar and cypress you can only remove a certain amount of growth – that why it can be better to replace a badly overgrown hedge, rather than attempt to salvage it.

Have a fertilizer program

Regular trimming removes green foliage, so to produce more your hedge plants have to grow more leaves. To do this quickly, and remain vigorous year after year, it pays to have a regular fertilizer program that you follow pretty closely. Use a method that suits your hedge – liquid feed when young, granular when older. Slow-release forms cost more but they save a lot of time, since most only need to be applied once a year. Choose a quality blend that is designed specifically for evergreen hedges, as it has the right balance of nutrients.

Water before trimming

Trimming during drought periods can be risky, as the sudden exposure of all those cut edges can cause desiccation and die-back. But sometimes we just have to do a job when we have the time to do it, and a long delay may leave hedges ragged and untidy. So if you have to trim when the ground is very dry, soak your hedge a couple of days before hand, so that the foliage is full of water. It will trim better too.

Stay safe

After all that, you want to come down from that ladder in one piece. So wear gloves to protect your hands, a hard-hat if you are up a ladder to any significant height. Make sure you have trimmers that have up-to-date safety features that protect you from injury, and if the weather is hot, make sure you stay hydrated.

What’s in the Bag? Understanding Evergreen Fertilizers

Spring and early summer are peak times for plants to grow. Some plants only grow at that time and spend the rest of their time maturing buds for the following year. Others grow continuously, but more slowly and less vigorously, outside of that early peak period. When we grow plants in our gardens we often want to have maximum growth, so our screens and hedges mature rapidly, and so our gardens look full and lush. This means that even if we take good care of our soil, so that most of our plants need nothing more, in a few parts of the garden we want to boost growth with something extra.

Supplementary fertilizer is especially useful with plants where we take something away from the plant regularly. This could be fruit or flowers, but it also applies to lawns and hedges. Whenever we clip plants they need extra food to make up for that, and to replace it with new growth. This is where fertilizers come it – to give that extra fillip to those plants we stress by harvesting – even if that ‘harvest’ is just a bag of hedge clippings.

Evergreen bushes in particular – both broad-leaf and conifers – need a particular balance of fertilizer elements, so when you go to the store for hedge food, you see that the makers have created something the call ‘evergreen food’, or something similar. So what is special about the needs of evergreens, and what is in that bag? Why should you buy this one, and not something else? These are all good questions, and ones that lots of gardeners ask, so let’s try and answer them.

Young growth needs Nitrogen

By law, fertilizer bags are labelled with the amount of the three essential plant nutrients in them. This ‘fertilizer ratio’ is the three numbers you will find somewhere on the labelling, that looks like ’18-5-11’, or some other set of three numbers. First of all, you will see that it doesn’t add up to 100%. That doesn’t mean the rest of the bag is ‘filler’, as some people believe. Those numbers are the pure elements, and the rest of the bag is the other elements that are bound up with them to create the specific compounds used. Take a look at the ratio on a bag of evergreen fertilizer, and you will always see that the first number is the biggest. This is nitrogen, the element that plants need to make proteins and DNA, and especially the pigment called chlorophyll, which is the magic chemical plants use to trap energy from sunlight, and then turn it into sugars for growth. Right at the heart of every chlorophyll molecule are nitrogen atoms, and since green plants have lots of chlorophyll, they need lots of nitrogen to make it all.

All those clippings from your evergreens that you rake up or blow under the hedge are green, so you are taking chlorophyll away from the plant, and with it the nitrogen needed to make more. It’s that simple. Of course the plant also needs nitrogen for the structural proteins in its growth too, but chlorophyll is the big user, and so plants lacking in nitrogen will have pale green or yellowish leaves, instead of the rich, deep-green foliage we admire – and want.

In artificial fertilizers that first number is often big – between 7 and 20, depending on the formulation. If you look at organic fertilizers, it is rarely more than 4. That doesn’t mean these fertilizers are weaker, it is instead a result of the measuring system. That number is the amount of nitrogen in a form that the plant can use immediately. Much of the nitrogen in organic fertilizers is locked up in the material, and it takes the activity of bacteria and soil organisms to release it. This is why the top manufacturers of organic fertilizers are adding those special organisms to their fertilizer, to guarantee that all the goodness will be released. It’s a useful extra, especially in poor soils.

Potash is good too. . .

The third number in the formula is potash, and especially if you live in an area with colder winters, higher levels of that nutrient are very useful, as they make your evergreens more resistant to low temperatures. This is because potash (or potassium as it should be called) raises the pressure of the sap inside the cells, making the walls grow thicker and tougher, and so better able to resist low those icy days. It also makes them more resistant to pests, so its always good to see a higher level. If you are trying to choose one food over another, it makes sense to go for higher potash, if everything else is similar.

What else to look for?

You might wonder why some bags of fertilizer are more expensive than others. There are a couple of possible answers – for example it could be that one is slow-release, saving you going out and applying it several times – but another common reason is that some contain micro-nutrients as well as the ‘big three’. These are especially important to get top rates of growth, especially in evergreens that you are clipping regularly.

The most important ones to look for are iron and magnesium. These will be listed lower down and they must be shown on the bag if they are there. Both of them are involved in that chlorophyll molecule again – so vital for good growth. Iron is part of the enzyme system that makes chlorophyll – so low levels mean the factory slows down, and production falls below the necessary levels for top growth. Magnesium is right inside the chlorophyll molecule itself – surrounded by that nitrogen already mentioned – so it’s a raw material, and without enough, again, production will have to fall if the supply chain is disrupted.

Finally. . .

That’s it really. When checking the bag, look for a high first number – nitrogen – or if the material is organic, look for microbes to help release it. Also check if it contains iron and magnesium, and a higher potash number (the third one) helps too. All the rest is window dressing, but now you can make the best choices, and give your evergreens the best possible care.

Good Summer Care of Thuja Green Giant

So you just planted that row of Thuja Green Giant? Congratulations, it’s the perfect choice for a a screen or hedge – but now you are wondering what to do next. So here is a check-list of things to do and watch for with your new planting, so that it grows as fast as possible – and that is fast – and soon looks like the image you had when you bought them.

Summer Care of Thuja Green Giant

  • Water regularly – soak deeply for several hours once or twice a week
  • Mulch – it controls weeds and conserves moisture
  • Feed it – liquid fertilizer is best for new plants
  • Trim lightly – don’t wait for it to reach full size before starting to trim
  • Relax – there isn’t much else to do with this easy-to-grow plant


The single biggest killer or growth-slower of new plants is lack of water. For the first season you need to keep watering close in to the stem of the plant, which is where the roots are. The biggest mistake with watering is to take the hose, with or without a spraying nozzle, and spend a few minutes spraying the ground. This water doesn’t penetrate very far at all, and the roots usually stay dry. Water needs to be applied slowly, so that it trickles down into the ground, and there are two ways to do that easily.

One easy way is to use an open hose, with the faucet turned down so it just trickles. Lay the hose a few inches from the stem and leave it for about half an hour. Check back and if the ground around the plant now looks thoroughly wet, move on to the next plant. If you do this once a week your plants should be really happy. At the height of summer, if there has been no rain and it is hot and windy, you may need to water twice a week – -check by scrapping back a bit of the soil to see if it is still damp or not.

The second method is a less work, so it’s a great choice if you have a longer hedge. Get a length of porous pipe and thread it back and forth around your plants, covering the ground with a sinuous line of pipe. You can use loops of coat-hanger wire bend over to anchor it in place and hold it down. It is best to do this before putting down mulch. This kind of pipe leaks all along its length, letting drops of water flow out onto the ground. How long it takes to soak the area depends on your soil, so you need to experiment, starting with an hour, and adjusting that time as needed. Adding a simple timer to the faucet makes it easy to do this automatically, even while on vacation, and once you set it up there is nothing more you need to do.


If you didn’t do it when planting, put down a 2 to 3-inch layer of coarse organic material over the root zone as mulch. This could be bark chips, shredded wood, shredded leaves, garden compost, or even straw. Not only does it reduce or prevent the growth of weeds, mulch keeps the soil cool, stimulating root growth, and it slows down the loss of water directly from the soil. Keep it clear of the stems and foliage and cover an area a couple of feet wide at least. You will probably need to renew it after a couple of years – it depends on the type of material you used. Once the plants grow and spread outwards the leaves that fall inside the plant will act as natural mulch, and you won’t need to do it anymore. Remember not to dig old mulch into the ground, as more woody kinds of materials rob the soil of nutrients as they rot down.


Your new Thuja Green Giant plants don’t yet have extensive root systems, so they can’t reach the nutrients in the surrounding soil. To keep them growing at their peak speed it is best to feed them for the first couple of years with liquid fertilizers, as these soak right down into the root ball, so the nutrients are available. The foliage can also absorb them directly, so some types can be sprayed directly onto the foliage. If you are unsure, use a half-strength mixture for the foliage, and full-strength on the roots. Once a month is usual, although you might get slightly better growth with half-strength every two weeks. Make the last feeding in mid-September, so the plants harden-off a little before winter comes. Choose a formulation that is blended for evergreen trees and that contains iron and other micro-nutrients. You will really see the difference with liquid feeding, no matter how well you have prepared the soil. That good soil preparation will pay off in future years, but it doesn’t have a big impact in the first season.


Although you want maximum growth, you also want to develop good structure in a hedge, so that it is durable and lasts for many years. So if you are planning a hedge you will clip regularly, start doing it the first season. Just take an inch off the top a couple of times through the season, and a little off the sides too, especially in the upper part, so that your plants slope inwards a little. Don’t be tempted to trim 90-degree sides. It doesn’t work well, as the lower branches will become thin over time, and you will lose that great lush greenness right to the ground that is the mark of a top-quality hedge. These light trimmings as the plants grow produce a dense structure that is resistant to storm damage, and won’t break under the weight of snow. Stop trimming in mid-fall, so that the growth slows naturally before the winter comes, to eliminate the risk of the tips burning if the weather turns cold suddenly.


These are all easy jobs, that don’t take long, but they pay off in spades, with top-speed growth, rich, healthy green foliage, and the best-looking plants around. Good care in the early years of Thuja Green Giant helps it become the great plant you want – it’s easy, so enjoy the summer.

Caring for Your New Thuja Green Giant

You took the big step and planted a new screen or a hedge of Thuja Green Giant, right? Or maybe you have used some as future large specimens in the corners of your garden. Whichever it is, you have made the right choice if you are looking for fast-growing, disease and pest free plants, that even deer leave alone. These first years are the most important ones, because after that your plants will be almost completely self-maintaining, unless you are planning to trim them regularly for a formal look. It’s during these years, especially the first season or two, that the foundations of an easy and successful future for your plants are laid down.

For the Best Growth of Your New Trees:

  • Water regularly – it’s vital
  • Fertilize properly – use liquid formulations
  • Trim right away – establish dense growth early

We will assume you did all the early steps properly – ground preparation, correct spacing, and good planting – but if not, you will find blogs on this site covering all these things in detail – assuming you haven’t actually put them in the ground yet. Here we are going to consider the important steps in caring for your new Thuja Green Giant plants for the first season or two, so they really get going with a bang.

Keep Watering

The biggest mistake made is to think that because these are tough, reliable plants, you can just plant them and forget them. Maybe you will get lucky, with good falls of rain spaced out nicely through the season, and everything will be fine if you ‘plant and walk away’. But it’s much better to give some simple basic care until your trees become established, and watering should be at the top of the list. Remember that your plants went into the ground with just the soil from their pots around their roots, and for the first little while that is the only soil available to them. So when the weather turns warm and dry, and the summer sun begins to shine, they will start to lose water from their foliage immediately. The only source for that water is the soil around the roots, although if you have planted well, and firmed the soil around the root-ball, that ball will suck some water out of the surrounding soil too. None the less, even if the soil looks damp, it pays to look after that root ball with a little extra care, until enough time has passed for the roots to grow out.

So once a week, or even twice a week if the weather is hot and dry, go along the row with a hose and let plenty of water trickle down close to the stem, soaking that hidden root-ball. Any excess will drain out into the surrounding soil, and this simple exercise, which doesn’t take long, is the best single thing you can do to guarantee the survival and good growth of your new trees.

Pay attention to the surrounding soil too, as the roots won’t grow out into dry earth. The best way, and the most water-wise, is to run a porous hose along the row of your new hedge, weaving it in and out of the stems as you go. This can stay in place for years, and it will quickly be hidden by new growth. By running the water directly on the ground, you get it exactly where needed, and you don’t lose it to evaporation, which happens with a sprinkler. Connect this trickle hose to a regular line, and turn it on for a few hours, until the water has soaked in and spread sideways. How often you need to do it will depend on the type of soil you have, how hot it is, whether you have used mulch (which is recommended), and how much rain has fallen. Don’t be fooled by light showers – scrape back a little soil to see if it is dry underneath, as it often is after light rain. Keep the soil damp, but don’t water until the soil is looking a little dry, as the roots won’t grow into a swamp!

Use Fertilizer

You probably enriched the soil when you planted – it’s highly recommended – but until the roots grow out that food is not available. Plants grown in containers are fed regularly with liquid fertilizers, and you will get the best growth from your new plants by doing the same. Choose a water-soluble formulation designed for hedges and evergreens, and use it as directed. If the directions are to apply monthly, you will get even better results by halving the concentration and applying every two weeks instead, as this gives a steadier supply of those vital nutrients. Start in mid-spring, as soon as you see signs of new growth, and flowers coming out around the garden, and keep feeding into early fall. Then stop, especially in colder areas, as you want your trees to finish growing in time for the new growth to harden off before winter. In warmer regions you can continue feeding until late fall.

Start Trimming Right Away

Since you want your plants to grow as much as possible, trimming might sound counter-intuitive. Some people wait until their plants have grown to their intended size before beginning to trim, but this is a mistake that can shorten the effective life of your screen or hedge significantly.

The best practice is to trim lightly almost as soon as you plant. Once you see a little new growth, take a sharp pair of shears and trim a little bit off. It doesn’t even have to be an inch of growth, and pay special attention to the top, as it will soon ‘run away’ if it can, leaving the bottom areas thin. This is something that cannot be fixed later, so slow down growth in height just a little, to build up bushy, broad plants that will stay green to the ground for decades. In fact, if your new plants have some wispy long upper growth, trim it back a few inches the same time that you plant.

Your goal should be broad, full plants with many branches right to the ground. Regular light trimming, taking a little more from the top than the sides, will make that happen. Taper the growth inwards a little, so that light reaches right to the bottom, and always do that for the life of your hedge and screen. During the first and second seasons you might want to trim lightly 4 or 5 times during the growing season, and since your plants are still small it won’t take long. Use sharp tools and just remove the tips from the new growth.


These simple steps are just a little extra work but a big investment in a great future for your plants. Your new Thuja Green Giant are going to do most of the work, so give them a helping hand – it’s a small effort that brings big results.