The Birch tree is related to the famous Oak family and grows in the north part of the northern hemisphere. It has a large number of varieties. It has very typical flowers, which are clustered together and are known as the ‘catkins’. It has green, oval or elliptical leaves with single or double serrations at the edges. The bark of the tree is unique with white, grey, silver, yellow or black color.
The fruit of the Birch tree, called a samara, contains millions of seeds. The wood of the tree is highly flammable. It finds applications in making furniture, toys etc. The tree secretes sap which is used to make beer and wine in northern Europe, Russia and China. The bark of the tree has therapeutic properties and is used in pharmaceutical industries.
It grows wild in the forest and is also planted for its various benefits and beauty.
Where do Birch trees grow best?
The USDA suggests zone 2 through 7 for the Birch trees.
The Birch tree is a hardwood deciduous tree that belongs to the genus ‘Betula’. In all, there are about 40 varieties of the Birch tree.
They are native to the Himalayas, Europe, USA, Canada and all over the Northern Hemisphere. Since they are distributed so far and wide in regions with different climatic conditions, the suitable growth conditions vary with the species.
Betula Papyrifera (Paper Birch), Betula populifolia (Grey Birch), Betula pendula (Silver Birch), Betula Lenta (Sweet Birch) need well-drained acidic soil for proper growth. Whereas Betula nigra (River Birch), Betula Utilis (Himalayan Birch), Betula occidentals (Water/red Birch) grow in absolutely wet and drenched soils with poor drainage.
Hence when you decide to get your Birch tree, check which soils suit it. Most of the varieties of Birch planted in the US need moist but well-drained soil. The pH value of the ground should be around 6 to 6.5, i.e. it needs to be slightly acidic. If the pH value goes beyond 7, it does not suit the Birch tree, and iron sclerosis develops.
Manage the pH value of the soil by adding lime if it is too acidic or sulfur to reduce the alkalinity.
The Birch tree does not like the sun on the roots because it dries up the soil, but the leaves want full sun. When you plant the Birch take care of this contradiction. Plant the Birch in such a way that the roots are in the shade and the upper part receives plenty of sunlight. Spreading mulch on the roots also helps manage this situation.
In the matter of temperature, the Birch tree is tolerant of the winters of zone 2 and summers of zone 7. All Birch trees may not work well in such a big range. It is always better to specify to the supplier the zone in which the tree is to be planted. Accordingly, suitable varieties can be selected.
How big do Birch trees get?
The Birch trees are medium-sized trees ranging from 30 ft to 70 ft. Some species reach up to 100 feet in the wild.
The height of the tree depends on the species, the soil, the climatic condition, and the surroundings. For all varieties of Birch (except the cultivars) the tree grows taller, healthier and has a longer life in the forest than in urban settings. It is the result of unpolluted air, water and naturally fertile nutritious soil. The tree will always thrive better in its natural habitat. When you plant a Birch tree, try to provide as close a surrounding as possible to its natural one.
The Betula occidentalis, Red Birch, grow tall up to 90 ft whereas the popular Betula Papyrifera (paper Birch) grows anywhere from 45 feet to a majestic 100 feet. The Betula Pendula (Silver Birch) reaches a height of 70 -75 feet. The Betula Platyphylla, Japanese white Birch has a moderate height of about 50 ft.
Betula Lenta, also known as sweet, black, cherry Birch grows to 40 -70 feet. Select a variety that will suit your requirement of height.
Which is the smallest Birch tree?
According to my research, what I found is that Betula Nana (Dwarf Birch) is the smallest Birch tree with a height of 6 inches to 36 inches. That is a minimal size and very popular for decorative purposes.
Betula nana is a native of the Tundra region in the Arctic. It grows in Greenland, Iceland, northern Europe and northern parts of North America. It thrives well in wet, but well-drained soil, that is acidic. Outside of its native land, it prefers to grow on heights of 1000 ft to 2700 ft.
Some parts of the Dwarf Birch are edible, and it has medicinal properties. It is best to check up with experts and specialists, before using Dwarf species as food or medicine.
The USDA zone 2 is ideal for the Betula nana.
How fast do Birch trees grow?
Some feel that Birch grows fast, while others find it a slow-growing tree. This difference of opinion is because different varieties have different growth rates.
But in general Birch tree grows at the rate of 18 to 20 inches per year. The rate of growth may also vary within the lifespan of the tree. It may initially grow slowly, and then the rate may pick up and towards the ends it may gradually reduce to reach the final maturity height.
For example, Betula nana (sweet Birch) grows 6 ft in the first 12 years. In the next eight years, it adds 40 ft to reach a height of 46 feet at the age of 20 years. Initially, it had a growth rate of half a foot per year, and in the next eight-year, the growth rate shot up to five feet per year. And then it finally reaches a height of 60 ft at maturity.
Betula Papyrifera (paper Birch) grows about 13 – 24 inches in a year. It has a bit higher growth rate as compared to others.
How long do Birch trees last?
The Birch trees have a life of 30 to 200 years depending on the variety and the species.
The soil and the surrounding, air and water have a significant bearing on the lifespan of the Birch tree. Birch trees live very well in their native environment as compared to other locations.
Betula Papyrifera (Paper Birch) lives a solid 140 years in its natural surroundings. But in the urban setting, its life cuts down to around 40 years. Paper Birch is tapped for its sweet sap, which is used as medicines and brewing alcoholic drinks. It is the reason for the shortened life of paper Birch. The sap is the life fluid of the plant and provides the necessary nutrients to the plant. If the sap of Birch is not tapped, it is bound to live longer and healthier.
Betula alleghaniensis (Yellow Birch) has a maximum life of around 300 years, with the average hovering around 150 years. Betula Lenta (sweet Birch ) has a good life of 250 years. These two varieties are among the longest-living Birch trees.
Betula Populifolia (Grey Birch) has an average life span of 150 years. Betula nigra (River Birch) possibly has the lowest life of around 25 years.
No matter which species of Birch you plant, water them properly, protect the roots, check soil conditions and give them space to grow, to allow them to live a full life.
Why is my Birch tree turning black?
It is definitely a sign of an unhealthy situation for the Birch tree. You need to pay attention to this situation immediately and implement the corrective measure.
The Birch tree may turn and appear black for one of the following reasons:
The leaves, twigs and branches get covered by a sooty (black, powdery) mold. It is essentially a collection of various fungi, which grow out of insect waste. Aphids, mealybug and other insects that inhabit the Birch tree release their waste on the twigs and leaves. Over a period of time, these wastes generate a mixed collection of fungi which is dark to black in color. Though in small quantities, sooty mold is no problem, but when the spread becomes extensive, it severely hampers the photosynthesis process of the leaves. Food production of the leaves drops drastically, and if not checked in time, will lead to malnutrition of the Birch tree. It can turn fatal for the tree. When spread all over the leaves, it makes the tree appear black in color.
As soon as you notice black spots on the Birch tree, spray some suitable insecticides to get rid of the insects that cause the black molds. If the insects are removed, further molds will not form. We have to take an indirect path to control the black mold because it is not possible to control the black molds directly.
It is popularly known as the leaf spot or leaf blight, and it is a fungal infection. When infected, the leaves turn brown and black and ultimately wither off prematurely. The tree appears dark/black in color when the fungus infects a large number of leaves. And this may make the tree very sick. Leaf blight incidence grows in warm and wet weather.
At a very early stage, a fungicide spray may be able to control it. But only fungicide spray is not sufficient. Immediately, all the infected leaves should be raked down and burnt off, a little away from the tree. If there are other Birch trees or any other tree in the vicinity, check them also for the leaf blight. You have to constantly keep a watch on the tree to see if the affliction is gone. If required, repeat the second round of fungicidal spray after a few days.
The leaf miner is an insect that sticks on the leaves of the Birch tree. It lays eggs on it and eventually the larva and the insect end up eating away the leaves. Brown/black patches appear on the leaves in the initial stages. In the later stages, the leaf withers off.
It is challenging to control the leaf miner insects. Spray some effective insecticides all over the tree. Along with this remove all the leaves with brown/black spots and burn them off to prevent the spread to healthy leaves and trees.
After planting the tree, occasional close inspection of the tree, its leaves, twigs and branches are essential to look out for any signs of infection or disease. You will have to scan all over your garden to check if some other plant or tree is sick. One infected plant in the garden will gradually spread to all the plants and trees.
To improve the immunity of the trees against such fungus and insects, use proper fertilizers as suggested by experts.
Are Birch trees easy to grow?
The Birch tree needs some care and attention to grow well. You cannot plant Birch and forget about it till it grows.
In some ways, it is very hard. Like it endures the cold and warm weather with equal ease. But it is not comfortable with all kinds of soil. Birch has to have well-drained moist soil. So mulching is needed.
Birch is drought-prone, and hence it has shallow roots which are always on the lookout for water in summers. Though it needs the soil to be moist, waterlogging should not happen. Hence the soil should be well-drained.
The roots do not like the intense sun, but the leaves demand full sun. The Birch is adaptable to a wide range of zones from 2 to 7 but is pest and disease sensitive.
If you are planning to have a Birch tree, you will have to manage these contradicting situations. It is not difficult to do it. But you will have to give it attention and time.
Since the Birch has a shallow root system, it does not like competing with turf, grass or such undergrowth. So keep the ground under the tree free of vegetation. The best thing to do is to apply mulch, so it protects the roots from the hot sun.
Keep the soil right, let the sun in, look out for symptoms of pest/disease, prune away dead and damaged parts of the tree
How do you keep a Birch tree small?
One cannot really morph a giant into a dwarf. But there are some simple and effective techniques, which can help reduce the height of the Birch tree to a reasonable extent.
Though it strikes as the simplest method to do, you should never prune the crown of the Birch tree to reduce its height. That way, you would end up stressing the tree, and it might not grow well at all.
The first practical method of reducing the height of the tree is to plant a multi-stem variation of the species that interest you. A multi-stemmed tree will always grow smaller than a single stem tree. It is because the life energy of the tree is involved in growing two or three stems instead of one. The tree will grow wide rather than tall.
The Betula Ermanii grows typically to a height of 65 -70 feet with a single stem. But if grown in a multi-stem, it reaches only up to 20 – 25 feet.
Another technique with the multi-stem is to cut off the leader stem. Now the tree grows with the subsidiary stems. Since the main/leader stem is gone, the thrust for height is lost. The tree remains short and spreads horizontally. This technique is popular with the Betula Utilis (Himalayan Birch)
In case you have a single stem tree and do not want it to grow very tall, use a large container to plant it rather than planting it on the ground. The Birch tree does not grow as tall in the box, as it does on the ground.
Cut the stems only in the autumn season. The flow of sap is minimum or negligent at those times. If cut in any other season, the Birch may bleed the sap to death.
In case you do not need a tall tree, you can also go for species with lesser height or pick up a cultivar to suit the height that you need. That way, you do not have to make any extra effort to keep it short.
How much space does a Birch tree need?
The Birch tree needs some good breathing space around it to grow healthy. Poor air circulation and lack of proper sunlight on the foliage significantly increase the chance of fungal attacks like the Anthracnose. There are two ways to decide the space that a Birch tree needs.
The first way is to take into consideration the spread of the tree, which is maximum near the crown. The plant supplier or the horticulturist should be able to give you a fair estimate of the foliage spread. Add a few feet to that, and that is the minimum space needed to prevent the rubbing of branches and leaves with another tree. Rubbing and abrasion lead to tree damage and wounds, and the risk of disease and insect attack increases substantially. The average height of the birch tree is between 40 to 70 and the width ranges from 35 to 60 feet. Considering an average width of about 48 feet, the average distance between the trees can behalf of that, which comes 24 feet.
The second method takes into consideration the spread of the roots. The thought here is if there are other trees within the circle of Birch tree root, it will lead to stress for the Birch tree, and it may not grow well. For any tree to grow to its potential, the roots have to develop fully and be healthy. Stunted roots will stunt the tree (that is the technique used in bonsai. The roots are not allowed to grow and spread much, so the height of the tree is short).
According to the experts, the spread of the root is directly related to the height of the tree. The diameter of the root circle is equal to the height of the tree. If the height of the tree, for example, is 50 feet, then the root will spread in a circle of diameter 50 feet. That means the roots would go 25 feet away from the tree on all sides. So, keep a gap of 25 feet surrounding the trees, to facilitate proper and healthy growth of the roots.
Some other considerations in deciding the space for the Birch tree:
- The multi-trunk tree spreads horizontally and will need more space.
- Weeping style Birch trees are generally broader than other styles. And hence they would also need more space. Some extra space should be left for the weeping style trees as they get damaged severely on rubbing against other trees.
If you have space constraints, leave space following the width of the foliage, as discussed in point 1 above. And if space is not a constraint, keep the gap equal to half the height of the tree (as mentioned in point 2 above.)
Do Birch trees have invasive roots?
Except for the Betula nigra (River Birch), the roots of the Birch trees are invasive.
The roots of the Birch trees are shallow and can easily damage the sidewalks, driveways and roads. Since the Birch roots do not like stagnation, in the summers when the soil drains away water, the roots seek water by spreading far and wide.
It senses water in pipes, sewers, drainages, tanks and tries to invade it, taking advantage of the minutest of cracks and crevices in the construction. Once it gets a hold, it splits the structure wide apart and claims the water. It is the survival instinct that makes it so aggressive in summers.
The roots of the Birch tree spread in a circle of diameter equivalent to the height of the tree. So, plant the tree so that the roots are away from any sort of construction.
To reduce the tendency and impact of the invasive roots:
- Water the tree to prevent any dry soil.
- Apply mulch on the ground above the roots, to keep the soil moist and cool
- Remove all turf and other growth from the ground just above the roots, so that the roots do not have any competition for water and aggressiveness will reduce to some extent.
Betula nigra and such species which grow near water and in ‘wet’ do not have such aggressive roots. There is no need for aggression and invasion as water is readily available. And even in drought they do not have this instinct of invasion and do not invade.