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Arborvitae (Thuja) Care Guide

Arborvitae (or as it is called – Thuja) is a very practical tree. Using these plants, you can form unique garden compositions or plant them separately, and it will also look very beautiful. Also very popular is the creation of a green fence from these plants.

My whole yard is surrounded by Thuja, so I have a lot of experience in growing them. Also, in my collection, there are many beautiful varieties, one of the most popular is Thuja orientalis Aurea Nana (Chinese Golden Cedar). In addition, Thuja occidentalis Danica grows in my garden, and it is shaped by a small tree. She has a very original look, a photo of which I will show in this article.

Emerald Green Arborvitae

And of course, His Majesty Emerald Green Arborvitae is a legendary plant that is widespread throughout the world, and probably everyone has seen it at least once.

So as you have already understood today, we will talk about Arborvitae and how to grow it. Here I will tell you everything I know about this wonderful plant.

Brief Care Information

Name Thuja, Arborvitae
Hardiness Zone (USDA) 4-7
Season Spring-Fall
Light Sun, Partial Sun, Shade
Width 3-5 feet
Height 3-30 feet
Pests Bagworm, Spider Mites
Disease Kabatina twig blight, Pestalotiopsis tip blight, Phomopsis twig blight
Water Drought resistant
Soil pH 6.0-8.0, Drained

The better the quality of seedlings, the better they will grow.

If you want your plants to grow without problems, then you should choose a good planting material. This may seem obvious, but you will be surprised to learn that not all sellers sell healthy plants. Let’s talk about it a bit.

It will be very good if you personally visit the nursery and choose the plants. The first thing you need to pay attention to is how everything is organized there. If there is everything in order and cleanliness everywhere, then it means that the sellers are neat people, and their plants are also good.

Then you can proceed to the review of plants. Externally, Thuja should be a deep green color (unless you buy a yellow variety). The needles must be clean and undamaged. Look in the middle of the crown; there may be insects. If everything is clean, then move on.

Look closely at the trunk and bark; it should not have deep cracks. The old bark may peel off a bit, but there should be no cracks through which the wood can be seen. Otherwise, it may indicate a plant disease.

Remove the plant from the pot and inspect the roots. There should be no insect larvae. A root system is a place where insects like to settle. Also, there should be no mold on the roots; otherwise, there may be problems with Thuja in the future.

Also, the roots should not be tangled. This often happens when the plant is transplanted into larger pots very rarely, and the root system does not develop properly and forms a dense ball. If you see such a plant, then refrain from buying.

Let’s say you bought a healthy Arborvitae and brought it home. Do not rush to plant it right away. Place the pot away from other plants. Then spray the plant first with a fungicide and a few days later with an insecticide. This is necessary in order to protect plants that are already growing in you from possible infection.

The half-shade is best suited for growing.

Thuja is one of the few conifers that can grow in the shade. Mostly all conifers love the sun and will not grow in the shade, but Thuja is an exception.

Full sun, partial shade, and shade will be suitable for this plant. It will grow in all conditions. However, the result will always be the same.

If you plant this plant in full sun, the color of the needles will be dark green and rich. Some varieties will grow a little slower, but all young shoots will ripen well. Also, yellow varieties in the sun will have a bright color of needles, but sometimes some of them can burn, especially in late winter.

In my opinion, the best place for planting Arborvitae will be partial shade. Plant it so that it receives direct sunlight for only half a day. As a result, the needles will be bright, and the plants will grow healthy, and the yellow varieties will not burn from excess sun. This can be achieved by planting a thuja from the east or west side of the house.

In full shade, these plants will also grow quite well. I have a green fence planted behind the building on the north side. The plants have been feeling well for several years. However, I must admit that they are not as thick as in the sun, and the color of the needles is a little lighter.

Spherical and columnar varieties are perfect for creating garden compositions. Columnar varieties are very popular when creating a green fence. It can even be grown as Nivaki or Bonsai.

Arborvitae likes a slightly acidic substrate.

In general, Thuja can grow on a wide range of soils, but on drained and slightly acidic soil, it will feel better.

If your yard has clay soil, then mix it with peat or compost in a ratio of 3 to 1. This will make it looser, and the roots will spread faster. In addition, peat will slightly acidify the soil.c

Compost can be used instead of peat. It also makes substrates looser and is a natural fertilizer. However, it is necessary to be careful here because improperly prepared compost can contain many pathogenic bacteria that can harm the plant. Therefore, if you have experience in making compost, you can use it for Thuja or buy good quality compost.

If sandy soils predominate in your area, then you need to make sure that the substrate retains moisture better. To do this, add a little compost to the mixture. The amount of compost depends on how sandy your soil is, but 10-15% is usually enough.

I have quite a clay soil in the yard. For some thuja, I prepared a mixture of earth, peat, and compost. However, there was not enough time for some, so I planted them in ordinary garden soil. So far, they are fine. Yes, they developed a little slower, especially in the beginning. However, after rooting and several years of growth, I did not notice much difference.

The beginning of autumn is the most favorable time for planting.

Planting time affects the growth of the plant and whether it will survive at all.

Spring is the most convenient time for planting. At this time in the garden, there is not much work, and you can pay more attention to individual plants. I recommend planting when the soil thaws and becomes warmer. This may be mid or late March. It is also not too late to plant in April.

If, for some reason, you did not have time to plant in the first half of spring, then in May, it can be done. However, I have had cases where plants have died due to too hot weather in late spring.

As I said in the title of this chapter, the best time is the first half of autumn. At this time, the conditions are softer, and the plant will be easier. The sun is not so strong, and the humidity is quite high. These are ideal conditions for the establishment of the plant.

However, you should not delay autumn planting. It should be planted at least a month before the first frosts.

I want to warn you against summer planting. Many gardeners claim that Arborvitae can be planted in the summer, and this is partly true. However, my experience suggests that it does not always end successfully.

In early and late summer, you can try to plant, and most likely, it will end well. However, I do not recommend under any circumstances planting these plants in mid-summer in the heat. Otherwise, there is a high probability of losing the plant.

You do not need to plant Thuja in winter. At this time, the plants are dormant, and there is no point in disturbing them.

If you need more information about the planting time takes a look: Arborvitae When To Plant?

When planting, do not cover the trunk with soil.

This is the main chapter of this article, so try to read it as carefully as possible.

I have already spoken about the time of year when it is better to plant. However, there is more to say. I recommend planting in cloudy weather or at least when there is no strong sun. The first few days should be as favorable as possible. Also, plant thuja in the morning or evening, it will make the rooting process a little easier.

It would be good if it rained before planting. If it has not rained, then you need to water the plants and the place where they will grow. Water several times to saturate the plants and soil with moisture.

Dig a hole twice the size of the pot in which the plant is located. If you have in the garden clay soil or groundwater high enough, then the pit should be three times deeper than the pot and need to create drainage. The drainage can be expanded clay, rubble, or stones. Fill the pit with drainage for a third; then, you can start planting.

Remove Arborvitae from the pot, trying not to damage the roots. Some recommend straightening the roots or even cutting it a little. I do not recommend doing this under any circumstances. Even minor damage to the root system can lead to plant loss. Conifers are very sensitive to such damage.

Planting Arborvitae

Pour the prepared soil into the pit and place the plant so that the surface of the potting soil is on the same level with the surface of your garden or slightly higher (1 inch). The reason why I recommend planting a little above the level of the garden surface is that over time the ground will settle, and the plant will deepen a little. You don’t want to dig the trunk into the ground because it can start to rot.

If, for some reason, you planted Thuja in sunny weather, I recommend shading it for a few weeks. It often happens that after planting conifers begin to grow and after a while die. Shading the plant will soften its conditions a little. You can shade the plants with a net, which can be found in every garden center.

Immediately after planting, you can water the liquid fertilizer. There are many good liquid fertilizers on the market, choose those that are designed specifically for conifers. Liquid fertilizer will give impetus to the plant.

On the first day, water the plant twice with a little water. Do not form a swamp around it and saturate the soil slowly. Then water from time to time, it is important that the soil was slightly moist. After three months, watering can be reduced and watered about once a week. All of the above is true only if there was no rain.

Thuja can withstand short periods of drought.

Let’s talk about how much water this plant needs after it has established in a new place.

After two years after planting, the plant should take root, and watering can not be done at all. Natural rainfall is usually sufficient. If there is a short period of drought, Thuja will withstand it. Exceptions may be periods of abnormal heat and lack of rain; then, the plants need to be watered.

In drought, the color of the needles becomes greenish-brown, and even the tips of some branches may dry out. In general, Thuja will survive the drought, but it will not look very nice.

I rarely water my Thuja. However, there are many moisture-loving plants growing in my garden, and when I water them, thujas also get water. I noticed that they respond well to watering. The color of the needles is deep green, and it grows more vigorously.

Therefore, I recommend watering these plants in the absence of precipitation. This situation usually occurs in the summer. You should water when the top layer of soil dries to a depth of 1 inch. From this, we can conclude that watering is needed two or three times per month. It is not necessary to water more often than once a week.

I recommend starting watering in the morning or evening. Also, it can be done in two stages, water not with a large stream but for a long time. It is necessary to saturate the soil with moisture so that it does not dry out quickly.

I will repeat that watering is necessary only in the absence of precipitation. If there was at least a little rain then watering is not needed.

At other times of the year, except in summer, watering is not required; usually, at this time, there is enough moisture.

For the best appearance of the plant, add fertilizer.

In the first few years, Thuja will grow relatively slowly; at this time, it makes sense to feed them. However, after full rooting, the growth rate will accelerate, and it does not need fertilizers.

The need for fertilization depends on the variety. Varieties such as Emerald Green Arborvitae and Green Giant Arborvitae require almost no fertilizer. The only time they should be fed is the first two or three years after planting. This will allow you to reach the desired size faster.

Dwarf varieties have a much lower growth rate. Varieties such as Fire Chief Arborvitae or Golden Globe Arborvitae have an annual growth of 6-10 inches. Therefore, if you want to accelerate their growth, you can add fertilizer.

I recommend fertilizing with mineral pellet fertilizers. One of the best is Osmocote. It has a balanced NPK formula and releases nutrients slowly. This feature will allow you to avoid frequent feeding. You need to apply 1.7-3.5 oz of fertilizer under each plant once a year, depending on the variety and size. You do not need to do anything else; the fertilizer will do everything for you.

You can also fertilize with organic fertilizers, such as compost. It can be added to the soil mixture at planting or mulch the surface around it. Use only quality purchased compost, as poor quality or improperly prepared compost can harm your plants.

It is also important to use only one type of fertilizer. Otherwise, it can lead to excess fertilizer and intensive growth. As a result, needles and branches will be brittle and more vulnerable to disease.

Do not fertilize Arborvitae in autumn. This can lead to the growth of new twigs, and they can be damaged by frost in winter.

I want to say a few more words about foliar fertilization. This type of fertilizer gives a short-term effect. The plants become bright green and lush, but for a short time. Therefore, this fertilizer is used mainly in nurseries for the sale of plants. At home, it makes no sense to do foliar fertilization.

Arborvitae is best propagated by cuttings.

Among all conifers, Thuja and juniper are most easily propagated by cuttings. This is due to the fact that between the bark and wood, they have a lot of cambium. Cambium is a tissue from which branches, needles, bark, or roots can be formed.

If you want to increase the number of your plants and not pay for it, you can propagate them by cuttings. To do this, you need to pluck 2-year-old twigs from the main branch along with the ‘foot.’ ‘Foot’ is the place where the cutting is attached to the main branch.

Cuttings should be plucked in early spring before new growth, but after the plant wakes up from hibernation.

Next, you need 8-10 inch deep containers with drainage holes in the bottom. Fill them 90% with sterile soil for seedlings.

Soak the lower ends of the cuttings in Rooting Gel and stick into the soil. Water them with plenty of water, and you can also slightly moisten the needles.

Transfer the containers to the greenhouse and shade it. For successful rooting, the humidity must be high, and the temperature must be at least 64.4 ° F (18 ° C). The soil around the cuttings should be moist all the time.

In a few months, the roots should appear. At this time, you can water with liquid fertilizer to give energy to new plants.

Plant the cuttings in a permanent place 1-2 years after rooting.

There are also two other ways to multiply Thuja. The first is the seeds. This way, you will not get plants with varietal characteristics, but the seedlings are usually very energetic and grow better than varietal plants. The second way is grafting. Rare varieties are propagated in this way, and in general, it is a complex method.

You need to protect plants from disease.

Thuja is quite resistant to disease, but sometimes they can get sick. Most often, it happens with dense planting or stagnant moisture. Let’s look at the main diseases and how to deal with them.

Kabatina twig blight manifests as small black spots on the needles. The cause can be plant damage or stressful conditions. As a result, needles and branches turn brown and die.

Control methods include removing the affected parts of the plant. Also, after pruning, you should spray the plant with a fungicide intended against this disease.

The next disease is Pestalotiopsis tip blight. It occurs as a result of a lack of sunlight and dense planting. First, the tips of annual branches turn yellow, and this extends to the base. Then the needles turn brown and die.

The plants should be planted in places where there are at least a few hours of direct sunlight to avoid disease. If an infection has occurred, remove the affected needles and branches. Then spray with an aqueous solution of a fungicide specially designed for this purpose.

Phomopsis twig blight is also a dangerous disease for Thuja. When infected, the tips of young branches begin to die, and the disease spreads further. Mostly this happens in the second half of spring or early summer. At this time, the most favorable conditions (high humidity and positive temperature).

If you notice these symptoms, immediately prune the affected branches with a sterile instrument and apply a fungicide labeled to combat the disease.

In general, I recommend spraying your Thuja with various fungicides several times a year. This will avoid most diseases, and in my opinion, it is better than treating the plants later.

Some pests can cause damage.

Thuja is not often damaged by pests, but you should still be vigilant. At the first sign of pests, you must act immediately. Let’s talk about who can threaten your plants.

First of all, it’s Bagworms. These insects love conifers, and Arborvitae is no exception. Fortunately, they are easy to notice, they form bags in which the larva hides. The size of these handbags is quite large, and you will see them without much effort.

If you have these pests on your plants, there are two ways to defeat them. The first is to collect all the larvae by hand and destroy them. However, if there are too many insects, then it will be difficult to do, especially if you have a lot of thujas and they are large in size.

The second way is to treat the plants with a systemic pesticide. The product will penetrate into the cells of the plant, and when the insects eat the plant, they will be poisoned. This is a tough but very effective way.

Another common pest that can parasitize on Thuja is Spider Mites. These are tiny creatures that belong to crustaceans. They can be seen on a tiny cobweb that they weave around the branches in the middle of the crown.

The first sign of their presence is the browning of one or two branches. If this has happened to your plants, then look closely for a thin cobweb and small red beetles on these branches.

If the result is positive, then you should act immediately. There is a lot of information that these pests can be removed simply by watering them with a stream of water. I do not consider it an effective method; it is rather a temporary solution. It is best to spray the plants several times with acaricide (this is a special product designed specifically against Mites).

The recommendation of this chapter is that you should take precautions and spray Thuja with pesticides to prevent pests.

Growing Tips

  • In columnar varieties, cut all vertical shoots except the central one. This will make the crown stronger, and it will not fall apart from the wind and snow.
  • In spherical varieties, cut all the shoots that grow up. This will make the crown more spherical.
  • Transplant thuja only in spring or autumn and in cloudy weather. When digging, try to minimally damage the roots.
  • Mulch Arborvitae with pine bark. The height of the mulch layer should be no more than 1 inch.