The carob tree, or simply carob, boasts a long tradition in our country. It is native to the Mediterranean basin and has always been part of the spontaneous vegetation. In ancient times, carob tree cultivation was one of our pride and joys. However, this agricultural practice has unfortunately been dwindling over time. Nevertheless, this plant remains an important cultivation that is worth rediscovering. And it can be done in a family orchard or garden, even for simple ornamental purposes. The important thing is to have plenty of space available, given its grandeur.
In this article, we will therefore see how to cultivate carob and get to know the botanical characteristics of the tree. Finally, we will explore the uses of its fruits: the famous carobs.
The scientific name of the carob tree is Ceratonia Siliqua. It is a tree belonging to the botanical family Fabaceae, subfamily Caesalpiniaceae, genus Ceratonia.
Origins of the Carob Tree
The exact origin of the carob tree is somewhat uncertain. It seems to have existed as a wild species in the territories of the eastern Mediterranean basin. According to this theory, the cultivation of the carob tree began with ancient Greek civilization, which then exported it to Sicily. Another reconstruction suggests that the Phoenicians planted it in Sicilian soil. Therefore, the tree’s origin should be located in the Middle Eastern region, in an area corresponding to present-day Lebanon. The fact remains that the tree is truly Mediterranean.
Where Carob Grows
Today, carob cultivation is a widespread practice, especially in southern Spain, Portugal, Greece, Cyprus, and North African countries. In Italy, it grows spontaneously in the central-southern regions and in Sardinia. It has also been naturalized in Tuscany. Apulia considers the carob a protected species. In Sicily, its cultivation is still practiced, as this region has the most carob trees.
Characteristics of the Carob Tree
One of the peculiarities of the carob plant is its longevity; it can live up to five centuries. It is a very large tree, capable of reaching heights of 10-12 meters, but on average, it reaches 5-6 meters. The root system is very complex, with a long and deep taproot that branches out thanks to numerous lateral roots. These roots are both creeping and deep. The carob tree grows well in difficult and rocky soils, so its roots have the ability to extend far to find water, beyond the tree’s canopy projection. This makes the tree perfect for soil stabilization on slopes. The tree bears fruit on branches that are 2 or 3 years old, leaving fruit bulges at the growth point. In the following years, fruiting is repeated at those same points. Over time, the bulges grow larger, forming distinctive bumpy surfaces.
The carob tree has an imposing trunk, rough and twisted, which in the largest specimens can exceed 2 meters in diameter. The bark is rough with large cracks at the base, smoother at the top. The color is gray-ash or gray-reddish. In mature trees, the canopy is dense and expanded, with a typical subglobose shape. The old branches can reach up to 7 meters in length and tend to curve, giving the tree its shape. Younger plants have branches that rise upward and are more regularly arranged.
The carob tree is an evergreen, meaning it never loses all of its foliage. The carob leaves live for over a year and renew periodically. They are symmetrically arranged on the branches, paripinnate, usually consisting of 4-6-8 pairs of leaflets. They have a short and thick petiole. They are also leathery, smooth, and shiny on the upper surface, paler on the lower surface. They have an entire margin, an oval shape, and are marked by prominent veins. Generally, they are 4 to 8 cm long and 3 to 6 cm wide.
In general, flowers provide information about the sex of a botanical species. In the case of carob flowers, this categorization is quite complex. This plant is, in fact, defined as polygamous-dioecious-trioecious. This means that there are specimens that bear only female flowers (fruit-bearing plants); others with only male flowers (sterile plants); and still others (rarer) that bear both male and hermaphroditic flowers. In general, the flowers of this tree are very small. They are grouped in racemes (solitary or aggregated) and are located on the large branches devoid of leaves. The inflorescence is 6 to 11 cm long. The male inflorescence is dark red when newly formed, becoming yellowish when fully mature. Conversely, the female inflorescence starts out reddish-crimson and matures to green-yellow. Their smell is very strong, penetrating, and not pleasant to everyone.
Pollination and Flowering Period
The flowering period of the carob tree is staggered, starting in August and lasting until the end of November. Pollination is partly entomophilous (performed by insects) and partly anemophilous (performed by the wind). The female flower has a very short stem, while the male flower is longer. The flowering process of the carob tree is curious. Each flowering point becomes a fruiting point. As a result, after flowering, the fruits will form only on those points where the inflorescence has sprouted.
Another distinctive feature of the carob tree is that the fruits, after the flower fertilization, begin to develop only in the following spring and mature in the months of August and September. So, it takes a whole year to collect them. When the fruits are ready for harvesting, the tree already has new flowers for the next year’s production. Carobs are nothing more than indehiscent legumes hanging on the tree, with the following characteristics:
- They have a variable length of 10 to 20 cm, width of 2 to 4 cm;
- Initially, they are light green with reddish streaks. As they mature, they turn first brownish, eventually becoming dark brown, almost black;
- The shape is arched and rounded, larger towards the ends;
- Tough and glossy skin;
- Fleshy pulp rich in sugars;
- The inside of the fruit consists of chambers that contain the seeds. These are ovoid in shape, flattened at the apex, up to 8 mm long and about 7 mm wide.
- The seeds are reddish and very hard. Each fruit contains 10 to 12 seeds, although there are varieties that contain 1 to 3.
The cultivation of carob trees in Sicily has an ancient tradition. Over time, native varieties have been selected.
These are specifically female varieties, which we list below:
If you want to cultivate a tree of this fruit, we recommend looking for one of these varieties at a specialized nursery.
How to Cultivate a Carob Tree
As mentioned, cultivating carob trees is an ancient farming tradition. Although this cultivar has been progressively abandoned today in favor of more profitable crops. In our opinion, the cultivation of this tree should be resumed, especially in marginal areas, where it brings great benefits to the environment. For example, it can play an important role in apiculture, as its flowers are very popular with bees due to the large amount of pollen and nectar they provide, and the flowering occurs at a time of year unfavorable for most honey-bearing plants. Its ornamental value should also not be underestimated, as the plant is beautiful and long-lived.
Here are the cultivation tips necessary for growing carob:
- The climate in which you decide to plant it should be mild, frost-free;
- The ideal soil is poor, limestone-rich, and alkaline;
- Avoid water stagnation;
- Sowing in a seedbed is preferred;
- During transplantation, use a wide spacing;
- Irrigation is necessary in the first year of growth;
- Perform simple maintenance pruning;
- Use biological control strategies to prevent pests and diseases.
To grow healthy and flourishing, the carob tree needs a mild climate. For this reason, it has always been cultivated in southern regions. It suffers from prolonged frosts when the temperature drops below -5°C for a long time. In areas where these unfavorable conditions occur, it is not recommended to cultivate the tree. The best exposure is in full sun (at noon), even in hot and dry areas, as it withstands drought well.
The ideal soil for the growth of the carob tree is a poorer one. It thrives remarkably well in rocky soils with a high content of active lime, with an alkaline pH. Another important characteristic is that the soils are well-drained and do not cause water stagnation. This is why these trees are perfect for rocky and sloping terrain.
The propagation of a carob tree can easily occur from the seed. The advice is to use a traditional seedbed. The best time for sowing is in April, when the risk of frost is behind us. The seeds, before planting, should be soaked in water for 3-4 days, changing the water every day. Sow in individual spots, 3 or 4, a couple of centimeters deep. The distance should be 30 cm, covering with a layer of fine soil. Once the seedlings emerge, thin them out and leave one per spot. When the plants are large enough, they should be transferred to the open field, being careful not to damage their delicate root system. This way, we will obtain a self-rooted rootstock. On the young plants created from the seed, grafting should be performed: shield budding if done in the same spring; or cleft grafting if done in the winter period. Also, remember that the carob tree is a dioecious plant. Therefore, to produce fruit, it requires cross-pollination, with the presence of at least one male specimen in the field. This characteristic is similar to that of the kiwi or the hazelnut. For example, if you plant two carob trees, one must be male and the other female. One male plant can pollinate up to 20 female plants. Consider the purpose of cultivation. If you want plants for ornamental purposes only, it’s fine to start from seeds using the methods described above. If you desire trees that bear fruit, it’s better to buy grafted plants from a nursery, already defined sexually.
When to Plant Carob
The best time to plant a young carob tree is in spring, after the last frost. Depending on the size of the pot it was raised in, you’ll need to dig a hole to place the sapling. To do this, simply follow the general instructions on how to plant a fruit tree.
In the planting of a carob orchard, you should consider the final size of the tree, as well as its extensive root system. The advice in a specialized carob cultivation is to maintain a distance of 20-25 m between trees in a row and 30 m between rows. In the case of planting a few trees, keep these measures in mind to avoid interfering with other crops. Also, avoid planting carob trees near water pipes, walls, or pavements. The deep and extensive roots could damage the plumbing network.
Irrigation is not necessary during the centuries-long life of a carob tree. However, in the first year of planting, occasional watering can be done to facilitate the initial root establishment.
In the wild state, the carob tree is not fertilized, yet it remains productive and thriving. Specialized cultivation has shown that carob benefits from periodic organic fertilization in terms of productive yields. This can be done with mature manure. Every three years, at the end of winter, about 40 kg of manure can be added to the soil.
The carob tree is a tree that should be allowed to grow freely, following its natural globular shape. Therefore, no real production pruning is done, but rather maintenance cuts. These are aimed at removing dry and damaged branches. The best time to intervene is at the end of winter. To give the tree a more balanced shape, with 3-5 main branches, an initial training pruning can be done. In the second year after planting, cuts are made on the central leader to leave only the branches of interest.
The carob tree is highly productive. However, a bit of patience is required before seeing the first fruits. These trees do not enter production before 10 years of age.
After this period, the productive yield increases significantly. Between 30 and 100 years of age, the tree is in full production. Annual yields can reach 200 kilograms per plant, although there can be years of alternating production. It works somewhat similarly to the olive tree, with years of heavy bearing and others less fruitful.
The harvest period for carobs is between August and September, when ripe fruits begin to fall to the ground. The tree can also be beaten with sturdy bamboo canes. However, care must be taken not to damage the flowers, which appear on the tree at the same time as the carob ripening. After harvesting, the fruits can be sun-dried or alternatively baked. These practices are used to make the carobs more appealing and therefore increase their commercial value.
Diseases and Pests
The carob tree is quite hardy and resistant to pest and disease attacks. However, there are some pathogens and insects to keep under control. Let’s see what they are.
The most concerning cryptogamic disease is carob powdery mildew, Oidium ceratoniae, also known as white mildew or mist. This is a form of powdery mildew that can be limited by preventive treatments with bicarbonate of soda. For very large plants, biological defense is challenging due to the difficulty of reaching all parts of the canopy.
Among the insects that can attack a carob tree are:
- Scale insects, especially Aonidiella aurantii;
- Lepidopteran species Ectomyelois ceratoniae, controlled using Bacillus thuringiensis;
- Exotic shot-hole borer Xylosandrus compactus, of Asian origin and still relatively unknown in Italy. Another plant it attacks is bay laurel.
Carobs in the Kitchen
Carobs in the kitchen have multiple uses. They are employed in confectionery transformation and in the industrial preservation sector. The most valuable parts of the fruit are the inner pulp and the seeds. From a well-dried fruit, about 90% of pulp and about 8% of seeds can be obtained. The remaining 2% consists of woody parts. From the pulp, you can obtain:
- Meal used in the production of animal feed;
- Flour for human consumption called carob cocoa. This flour is widely used in confectionery production and is appreciated for its pleasant taste and low fat content.
From the seeds, another type of flour is produced, which is used as:
- Suspending agent;
- Film-forming agent;
- Waterproofing agent;
- Homogenizing agent;
- Sedimentation agent;
- Filtration agent.
Another use is for the production of edible alcohol. Let’s not forget that they can also be consumed as dried fruit. If you want to taste this fruit, you can find various products here.