What are the characteristics of the acacia tree?

When you have a piece of land and you want to create a garden with fast-growing plants that give very good shade, it is very interesting to choose to plant an acacia tree. If the conditions are right, it can grow at a rate of half a meter a year, and it is also not necessary to water it very often as it resists drought.

If you would like to know more about him, I will tell you what are the characteristics of the acacia tree so you can identify it every time you go to a nursery or visit a garden. In this way, you can get ideas on how to design yours with this beautiful tree.

What is an acacia?

Acacia is a genus of trees and shrubs that belong to the botanical family Fabaceae, subfamily Mimosoideae. There are some 1400 species accepted, although there are more than 3000 described worldwide. It is, by far, one of the most widespread. It can be found in tropical and subtropical regions of the entire planet, especially in Africa and Australia. In the case of Spain, the acacia dealbata, being even feral in some points, and the acacia saligna.

Their height depends on the species, but they usually grow from 5 to 10 meters. Let's see in detail what its parts are:

Leaves

The leaves can be perennial or deciduous, depending on the climate in the area. Thus, those species that live in places where at some time of the year it does not rain and it is also very hot, they will drop the leaves in order to survive, as is the case of the A.tortilis for instance; On the other hand, those that live in places where they can have water and do not have problems with heat or cold, will produce new ones throughout the growing season.

If we talk about the size, in the vast majority of species they are small, no more than ten centimeters in length, but there are some, like the plant acacia saligna, which produces them up to 20cm in length. They can be lanceolate or paripinnate, that is to say, be composed of very small leaflets. Colors vary, and can be light green to dark green.

They sprout from prickly or unarmed branches.

Flowers

The flowers are grouped in racemose inflorescences. Each one of them looks like a miniature pompom, about 2-3cm in diameter, yellow in color. They are mostly hermaphrodites, but there are some who are unisexual.

Seeds

The seeds are found in a dried fruit that can be flattened or sub-cylindrical. They are found in large numbers (minimum 10) and germinate fairly quickly. In fact, you only have to subject them to thermal shock, that is, put them in boiling water for a second and 24 hours in water at room temperature, and then sow them in a seedbed with black peat mixed with perlite, and in a matter of a week they will begin to germinate.

Branches and trunk

The wood of this tree is quite hard. The log, although it grows very fast (some species are capable of growing at a rate of 70cm per year), by staying well anchored in the ground it is one of the strongest and hardiest of all fast growing trees. It is, therefore, a highly recommended plant to have in gardens where the wind blows regularly.

Likewise, branches after a few years remain flexible but are not the type to break easily. In fact, wood is used to build furniture of all kinds: tables, chairs, stools ...

Roots

The root system of acacias is very strong. Living in areas where rainfall is often low, its roots are not only able to penetrate well into the ground but also spread. For this reason, nothing should be planted near them. At a minimum, we have to leave a distance of 3 meters between the tree and any other plants that need regular fertilizers, and about 7 meters from any construction and pipes.

Main species of Acacia

We show you the three main species of this incredible genus:

acacia baileyana

La acacia baileyana It is an evergreen shrub or small tree native to Australia that reaches a height of between 3 and 10 meters known as mimosa or common mimosa. Its leaves are bipinnate, ash-colored, greenish-grey or bluish. It is one of the first to bloom, since it does so in mid-winter. Resistant up to -10ºC.

acacia dealbata

La acacia dealbata It is an evergreen tree native to Australia and Tasmania that reaches a height of between 10 and 12 meters. Its leaves are bipinnate and are made up of up to 40 pairs of leaflets with a glabrous upper surface and a tomentose underside. Blooms from mid-winter to early spring. Resistant up to -10ºC.

acacia longifolia

It is one of the tallest species: it can grow up to 11 meters. It is known as Acacia trinervis, Double Aroma, Golden Mimosa, Golden Wattle, Sallow Wattle, and Sydney Golden Wattle, and is native to Australia. Its leaves are evergreen and long, up to 20cm long, dark green. It blooms in spring and resists up to -8ºC.

acacia care

If you would like to have an acacia in your garden, write these tips:

• Location: outside, in full sun. I insist, plant it as far away as you can from any construction and pipes to avoid problems in the future.
• Land: not demanding. It grows well in poor soils, even those prone to erosion.
• Irrigation: during the first year it needs at least one weekly watering, but from the second it is not necessary to water it.
• Subscriber: It is not necessary. The only thing, if you dare to plant bromeliads or any other type of shade plant, you have to pay them regularly, otherwise the acacia will "steal" the nutrients.
• Plagues and diseases: they are very resistant.
• Transplant: in spring.
• Multiplication:
  • Seeds: in spring. After the thermal shock that we explained before (having them 1 second in boiling water and 24 hours in water at room temperature), you have to sow them in a pot with universal growing substrate. Cover them with a layer of soil so that they are not exposed directly to the sun, and keep them watered. Do not put too many in the same container, because when growing so fast it will be very difficult to separate them later. Ideally, put no more than 3 in a 10,5cm diameter pot.
  • Cuttings: in spring. You simply have to cut a piece of branch that measures at least 40cm, impregnate the base with rooting hormones and plant it in a pot with universal substrate mixed with perlite in equal parts. Keep it watered and in a place protected from direct sun, and after a month it will emit the first roots. Leave it in that pot for at least that year; so you can get stronger quickly.
• Pruning: It's not necesary.
• Rusticity: It depends on the species, but those that we can find in Spanish nurseries easily withstand frosts down to -10ºC.

Can you have a potted acacia?

Well, I had several years a acacia saligna, but she was barely growing and she didn't look pretty. It had a very thin trunk, about 0,5cm thick, and several branches that were too long. When planted in the ground, it only took two years for it to become strong. Its trunk thickened rapidly, measuring about 5cm, it gained height (3 meters) and many branches sprouted from it. Today it has been planted in the garden for about 6 years and looks like a Weeping Willow. Its crown measures almost 5 meters, and both hands are needed to embrace the trunk (from the base).

So yes, you can have it in a pot for a few yearsBut sooner or later he will end up "asking" for a floor. Perhaps the one that lasts the longest is the acacia dealbata, or the acacia tortilis, because having very small leaves you can prune them and shape them as you want. Moreover, although it is not very common, there are those who are encouraged to work them as bonsai. The ones that I recommend you discard are all those that have whole and long leaves, since these tend to have a greater development that is not so easy to control.

The care is as follows:

• Location: outside, in full sun.
• Substratum: universal substrate for plants, even if you are going to work it as bonsai. Or if you prefer, mix 70% akadama with 30% kiryuzuna.
• Irrigation: biweekly.
• Subscriber: in spring and summer with liquid fertilizers. I advise to use guano, for its rapid effectiveness.
• Transplant: every two years.
• Pruning: late winter. You have to remove dry, diseased or weak branches, and trim all those that have grown excessively. The crown of the tree should be rounded or parasol.

Acacias are very fast growing trees that look great in gardens. But, as we have seen, it is very important to take into account some things to be able to enjoy them for many years, since otherwise problems would soon arise. I hope this article has helped you get to know these often misunderstood, but magnificent trees better.