Monthly Archives: August 2018

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.

 

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.

Climate

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.

Weather

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.

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!

Screening is a key issue for many garden owners, for both privacy and protection of your garden. Everyone want to be able to use their garden without strangers – or neighbors – watching their every move, and very often to achieve that plants are the best option. Screening is not only visual, and there are several other important reasons to plant screening trees:

  • Visual Screening – evergreen plants provide the only practical solution when screening more than 6 feet tall is needed. A fence does not block second or third-story windows, but fast-growing trees can do that within a few years. As well, green, living screening trees are much more attractive than fences, last decades longer, and are much lower maintenance too.

There is more to screening than just blocking neighboring homes that might look into your garden. You may be near a highway, an industrial zone, rail-tracks, power plants, or other unsightly but essential city features. A tall planting can and will obscure even large structures, turning an unattractive aspect into a calming wall of green. When you come to sell your property, the disappearance of that eye-sore will have increased the value of your property greatly, for just a minimal investment in a few trees.

  • Noise Screening – many homes are built along busy roads or backing onto highways. You may be near a car park, with regular comings and goings, or even in the countryside there can be barns and active farming areas. Industrial parks too can generate noise, both day and night. Noise pollution is a serious problem, but plantings of evergreen trees filter and reduce noise levels more effectively than any other equivalent structure. The dense, irregular structure of a wall of green absorbs noise far more effectively than any hard surface of wood, metal or concrete. Installation is easy, and the cost is just a fraction of any other solution.
  • Air Pollution Screening – dust and atmospheric pollutants are absorbed by plants very effectively. Dirt particles are trapped by the complex layers of foliage, and then later washed into the soil by rainfall. Numerous pollutant gases, from carbon dioxide to methane, or are absorbed by the foliage, incorporated into the structure of the plant, and may remain in the wood for decades, or drop with foliage and be re-cycled into the earth. Nothing does this as effectively or cheaply as plants.
  • Heat Screening – because plants loss water into the atmosphere by evaporation, they cool the air around them. Evaporation absorbs heat from the surroundings, so it is automatically cooling, and much cheaper than air-conditioning. Unlike solid surfaces, which raise the temperature of areas near them by reflecting heat, plants absorb it, so the enclosed area will be cooler than an open space, and much cooler than an area screened with walls and fences.
  • Wind and Snow Screening – the porous structure of screening plants absorbs the energy of wind, rather than just deflecting it, or even amplifying it, as hard surfaces do. That slowing of wind extends many feet on the sheltered side of the plants, so if you live in an open, windy spot, a row of evergreens on the windward side will create a calm haven around your home. As well, that fall in wind-speed means that snow drops to the ground near the screen, instead of drifting towards your house, so you will have less snow built-up on driveways, paths, and around buildings. This means you have less snow to clear, and saves you time and effort in winter

Why Thuja Green Giant for Screening?

Screens all year round

You can get screening from almost any tall plants, but there are several reasons why Thuja Green Giant is the ideal choice. To begin, it is evergreen, so the impact is seen all year round. Deciduous screening may be attractive in summer and even fall, but in winter it is bare, and although the network of branches does still exert some effect on wind, your visual screening is almost completely gone. So evergreens make a lot of sense. Thuja Green Giant forms an evergreen wall of dense foliage, that is an attractive green color all year round. Many other evergreens can turn bronzy in winter, looking less attractive, or they may become scorched in either very cold or very hot conditions, needing care and looking unsightly.

Grows faster than anything else

As well, Thuja Green Giant is the proven fastest growing evergreen screening plant available. There are faster growing deciduous plants, like willow, but among evergreens nothing beats this plant. It can add 3 feet or more in height during its early years, and averages more than a foot a year right up to maturity. A ten-foot screen takes 5 to 7 years to create, depending on the size of the plants you start with.

Grows large enough to screen anything

Mature Thuja Green Giant plants will be 30 feet tall, and that will provide enough height for screening out almost anything. Yet it stays green right to the ground, so that vital eye-level area will always be blocked. This plant retains its dense structure for ever, unlike trees such as spruce or pine, which often become more open with age, and lose lower branches. This means that if you space your plants correctly, you never need to trim to keep your screening dense – which is a huge saving in time and dollars over any time-frame you choose to measure. Plus, if you do prefer a more formal hedge-like look, and a lower height, then this is a very easy plant to trim, responding well by growing denser, looking attractive right after trimming (unlike plants with larger leaves) and capable of being trimmed at most times of the year.

Grows in a wide range of conditions.

From zone 5, with cold, snowy winters, all the way into zone 8 or 9, with little or no winter at all, Thuja Green Giant performs well, without winter damage. It is drought resistant too, and once established needs no supplementary care. It is also virtually pest and disease free, and unlike many other evergreens, deer usually leave it alone as well. It grows in almost any kind of soil, except for ones that are constantly wet, and it tolerates a range of soils from acid to alkaline. Good soil preparation pays dividends in health, density and speed of growth, but even plants put into the ground with minimal preparation thrive and establish themselves well.

Easily obtainable at competitive prices

Because Thuja Green Giant is widely grown, in large numbers on a commercial scale, easy availability of plants in a range of sizes to suit your needs is always there. Prices are competitive too, although avoid ‘bargains’, as these will often be very small, or have open, thin foliage. Buy from a reputable, established company, and look for free shipping, so that you don’t see a big extra charge at the bottom of the bill. With on-line nurseries offering the best prices for top-quality plants, you can have those trees right at your door in a matter of days – just time enough for you to get the holes ready!