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.
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!