Thuja, more commonly known as arborvitae, are popular evergreen trees in the Cupressaceae family. These dwarf to large-sized conifers are used extensively in landscape plantings in our area, as well as in the Midwest and West.
American arborvitae and Western red cedar are two of the five species of Thuja. American arborvitae is a relatively small tree that grows 30 to 60 feet in height, while Western red cedar is a much larger tree, growing to heights of over 200 feet.
Arborvitae are popular among many people in the Northeastern United States because they grow rapidly and can be easily bought by the home gardener. Most arborvitae keep their branches close to the ground, making them ideal for hedges or screens. They are also usually resistant to insects and diseases.
The weather is getting wetter and warmer, which is making it harder to grow certain plants. People need to be more careful when choosing a plant for their garden, making sure it is suitable for the conditions. Arborvitae need moist soil that drains well, and if they are not in these conditions they are likely to get sick and not look very good. Areas where water pools after it rains are not good for these plants, and they are also a target for deer.
When choosing an arborvitae, it is important to pick a species and cultivar that will last a long time and be easy to take care of. Some arborvitae can change color in winter or lose their leaves, which can make them look old and ragged.
Selecting arborvitae
According to the text, which of the following is true? A.Thuja occidentalis is native to areas with cool, moist summer weather. B. Thuja plicata will not grow well in the hot summer conditions above USDA zones 7 or 8. C. Thuja plicata is much better adapted to the conditions of our area than Thuja occidentalis. D. Other Thuja species are difficult to locate for your garden. B. Thuja plicata will not grow well in the hot summer conditions above USDA zones 7 or 8.
When shopping for container-grown or balled and burlapped conifers, avoid those with thick mats of roots on the soil surface or roots circling around the main stem. A plant’s root flare should never be buried below the soil surface. Select plants with moist root balls that don’t have large, torn roots sticking out. Smaller plants are generally a better choice, unless you’re planting in an area with heavy foot traffic or you want a dwarf conifer that will reach the desired size more quickly.
Some popular cultivars, or variants, of Thuja that are well suited for gardens on the east coast of the United States are listed below. However, there are many more cultivars out there. The New York Botanical Garden is home to more than 30 varieties of Thuja, including examples from the species T. standishii (Japanese arborvitae), T sutchuenensis (Sichuan arborvitae), and T. koraiensis (Korean arborvitae). Come for a visit to see how these plants look when they mature. You can find locations of arborvitae gardens through the NYBG Garden Navigator.
- Thuja occidentalis ‘DeGroot’s Spire’ – an interesting, narrow cultivar with twisted foliage and wavy margins. Grows 6 or more inches a year, reaching 5 to 10 feet tall. Bronze in winter. Hardy in USDA zones 3 to 7.
- Thuja occidentalis ‘Hetz Wintergreen’ – a robust, narrow cultivar with superior strength under snow loads. This tree grow 12 to 18 inches per year to a size of 12 to 15 feet, and half as wide, at maturity. Retains good color in winter. Hardy in USDA zones 4 to 8.
- Thuja occidentalis ‘Lutea’ (George Peabody arborvitae) – a conical cultivar with foliage color changing from yellow when new, through gold tones to green. Grows more than 12 inches per year to a size of 12 feet and taller. Hardy in USDA zones 4 to 8.
- Thuja occidentalis ‘Smaragd’ (‘Emerald Green’) – a popular, narrow cultivar, that maintains its emerald green color very well in the winter. This tree grows up to 12 inches a year becoming a 6 to 10 foot plant at maturity. Hardy in USDA zones 4 to 8.
- Thuja occidentalis ‘Techny’ – a compact cultivar with excellent, dark green, winter color retention, growing up to a foot a year to reach 10 feet at maturity. Hardy in USDA zones 3 to 8.
- Thuja occidentalis ‘Wareana’ (Ware’s arborvitae) – a dense, conical, slow-growing, dwarf cultivar with superior hardiness. Grows only 1 to 6 inches a year but will eventually reach up to 10 feet. Retains winter color quite well. Hardy to USDA zone 4, and if well mulched, zone 3.
The better the quality of seedlings, the better they will grow.
It’s important to select healthy planting stock to avoid problems later on. This might seem like an obvious choice, but you may be surprised to learn that not all sellers offer healthy plants. Let’s discuss this in more detail.
You should visit the nursery to choose the plants. The first thing to notice is the organization and cleanliness. These factors suggest the seller is reliable and the plants are good.
If the Thuja you are looking at is deep green in color and the needles are clean and undamaged, then you can move on to the next step in the review process. Check the middle of the crown for insects. If there are none, then the Thuja passes this part of the review.
When examining a tree, you should pay close attention to the trunk and bark. If there are deep cracks in the bark, it may be a sign of a plant disease. Additionally, the old bark may peel off a bit, but there should be no cracks through which the wood can be seen.
Remove the plant from the pot and check the roots for larvae or mold. Having either of these on the roots can cause problems for the plant in the future.
Also, avoid buying plants with tangled roots, as this often happens when the plant is only transplanted very rarely into a larger pot, and the root system doesn’t have time to develop properly, resulting in a dense ball.
If you bring home a healthy Arborvitae, don’t immediately plant it. Place the pot away from other plants and spray it with a fungicide, then a few days later with an insecticide. This will protect other plants you have from possible infection.
The half-shade is best suited for growing.
Thuja is one of the few conifers that can grow in both full sun and partial shade. Most other conifers need full sun to thrive, but Thuja is more versatile.
This plant can survive in any type of light exposure; however, the outcome will not change.
The plant should be placed in full sun for the needles to be a dark green, which will enrich the color. Some varieties may grow more slowly, but all young shoots will mature well. Also, the yellow varieties in the sun will be a brighter color, but sometimes some of the needles can become discolored from the sun, particularly in late winter.
I believe that partial shade is the best place to plant Arborvitae. Plant it so that it only receives direct sunlight for half the day. In doing so, the needles will be bright, the plant will be healthy, and the yellow varieties will not be scorched from too much sun. To achieve this, plant a thuja on the east or west side of the house.
You can grow these plants in full shade and they will do fine. I have a fence that is planted with these on the north side of the building and they have been doing well for a few years. Although, I will say that they aren’t as thick as they would be if they were in the sun and the needles are a little lighter in color.
There are two main types of trees that are popular for gardens – spherical and columnar. Columnar trees are especially popular for creating a green fence, and can even be shaped into Nivaki or Bonsai.
The beginning of autumn is the most favorable time for planting.
When a plant is sown affects its growth and whether it will live.
I recommend planting in the spring when the soil thaws and warms up, which is usually around mid to late March, but April is also not too late.
If you didn’t have time to plant in the first half of spring, you can try to do it in May. However, if the weather is too hot in late spring, the plants might die.
The best time to plant is during the first half of autumn when the conditions are more ideal. The sun isn’t as harsh and the humidity is higher, making it easier for the plant to establish itself.
This will give it time to establish root growth. You shouldn’t wait to plant in the fall; it should be done at least a month before the first frost to give it time to establish roots.
I don’t recommend planting Arborvitae in the summer. I’ve had bad experiences with it in the past.
Don’t try to plant in mid-summer because it’s too hot and you’ll probably kill the plant.
Planting Thuja is not necessary in winter since the plants are dormant and there would be no benefit to disturbing them.
When planting, do not cover the trunk with soil.
I have already mentioned that the best time of year to plant is during the spring. However, there are a few more things to consider. I recommend planting thuja during cloudy weather or, at the very least, when there is no strong sunlight. The first few days should be as favorable as possible in terms of weather conditions. Additionally, it is best to plant thuja in the morning or evening, as this will make the rooting process a little easier.
It is best to water the plants before planting them. If it has not rained, then you will need to water the plants and the area where they will be growing. Water the plants several times to saturate the plants and the soil with moisture.
To plant a tree, first dig a hole that’s twice the size of the tree’s pot. If your garden has clay soil or if the water table is high, make the hole three times as deep and add drainage. The drainage can be expanded clay, rubble, or stones. Fill the hole one-third full of drainage material, then plant the tree.
Remove the arborvitae from the pot, being careful not to damage the roots. Some people recommend straightening the roots or even cutting them a little, but I wouldn’t recommend doing this under any circumstances. Even minor damage to the root system can lead to the death of the plant. Conifers are very sensitive to such damage.
Fill the hole with prepared soil until it is level with the surrounding garden or slightly higher, then place the plant so the level of potting soil is even with the top of the hole. I recommend planting it a little higher than the level of the surrounding ground because over time the ground will settle, causing the plant to sink lower. You don’t want the trunk of the plant to be buried in the ground, as it can start to rot.
Browning anytime
- Oversaturated soil: plants may be drowning from water soaked soil and poor drainage, due to improper siting or preparation. Roots cannot grow if they are constrained by dense soil which may also may create a “bathtub” around the root ball. In wet weather, water fills the air spaces in the soil and does not drain, choking off oxygen and damaging the roots. Needles and entire branches die-back. Mulching excessively creates a similar, overly wet, situation.
- Dog damage: should be considered if you have pets in the area and needles are browning under a 2 foot high mark. Repeated urination can darken needles and will even affect the soil and overall plant health if the problem is persistent.
I recommend spraying your Thuja with various fungicides several times a year to avoid most diseases. I think it is better to do this than to treat the plants later.
