Garden Oracle / Drought and Heat Tolerant Gardening / Tucson - Phoenix - Arizona - California

Growing Carob:
Ceratonia siliqua

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Botanical Overview

A member of the legume family (Fabaceae), the Ceratonia genus has one species, Ceratonia siliqua: Carob. About 50 cultivars have been developed around the world.

Description

Form: Tree.
Lifespan: 80-100 productive years.
Leaf retention: Evergreen. Some leaves may turn yellow and drop in severe drought situations.
Growth rate: Slow to moderate.
Mature Size: 30-40' (9-12m) high and as wide or wider.
Flowers: A few cultivars have bisexual flowers that are self-fruitful. Most have separate male and female flowers, with a course bottle-brush structure, on different trees. The male flower parts and flowers have a semen-like odor, mild to some, strong to others, to attract insects. Pollination is by wind and insects. The flowers appear on spurs of old branches and on the trunk.
Bloom: Fall.
Self-fruitful: Some cultivars are bisexual and self-pollinating, others need both a male and a female tree to produce fruit. Male trees do not bear fruit.
Years before fruiting: 6-7 years.
Fruit: A long, green turning to brown, edible seed pod with a chocolate flavor when ground.
Months for fruit to ripen: 11. Dried pods should be harvested quickly after they turn fully brown if rain is likely. Brown pods ferment on the tree when they become wet.
Yield: Pod yield increases with the age of the tree: 5 lbs (2.3 kg) at six years, 100 lbs (45.4 kg) at twelve years, up to 500 lbs (226.8 kg) at twenty years for some cultivars with certain orchard management techniques.
Storage after harvest: Keep in a dry, ventilated location. The pods can be stored for several months.
Leaves: Oval, green, thick leaflets, providing heavy shade.
Stems: No thorns.
Roots: This tree has a deep tap root and aggressive surface roots.
Cultivars of Note:
'Clifford' Self-fruitful, excellent flavor, large crop with irrigation.
'Santa Fe' Self-fruitful, excellent flavor.
Most nurseries sell self-fruitful carob trees without a cultivar name. Check to make sure whether the tree is self-fruitful, a male, or a female. The self-fruitful will smell when flowering and have seedpods. The male will also smell but have no seedpods. The female will not smell when flowering and will have no seedpods without a male or a self-fruitful tree being present.
Wildlife: The flowers attract insects. The seedpods are eaten by mammals.
Toxic / Danger: No. Unlike chocolate, the seedpods of the Carob tree are safe for animals and dogs to consume. The seedpod husk and seeds contain some tannin, but no caffeine or theobromine.
Origin: Mediterranean region.

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Cultivation and Uses

USDA hardiness zones: 9-11. Young trees suffer frost damage. Older trees are hardy to 20°F (-6.7°C).
Chill hours: None.
Heat tolerant: Yes.
Drought tolerant: Yes.
Sun: Full sun. This tree is shade intolerant.
Planting: Locate the tree where it will get full sun all day, no shade, and the soil is well draining. Avoid any area getting frequent irrigation, such as a lawn. Mature trees in the ground cannot be transplanted because of their taproot. Surprisingly, this tree can be grown in a large container.
Soil: It needs well drained soil, but is tolerant of soil types otherwise. A pH of 6.2-8.6 (slightly acidic to alkaline) is best. This tree is salt tolerant.
Fertilize: Fertilization is unnecessary, but organic fertilizer can be applied once a year in late winter. Carob trees are highly successful in their ability to extract nutrients from poor soil.
Water after becoming established: Deep water once a month from the third year on. Seedpod production requires slightly more frequent irrigation, but in summer, this tree needs irrigation reduced to once a month. It evolved in a region with moderate winter rain and infrequent summer rain. It is prone to fungal infections in soil that does not dry quickly or is watered too frequently.
Mulch: Never. The soil must dry quickly and this tree's roots tolerate high temperatures.
First Two Year's Care: Deep water weekly in warm months during the first year in the ground to establish a strong root system. Deep water at least every two weeks in the second year.
Prune: Flowers appear on old wood and the trunk. Trim branches that touch the ground and dead wood from the previous winter. Trim lightly to shape in the first few years. Carob trees generally do not need pruning.
Litter: Moderate: flowers, leaves and seedpods.
Propagation: Carob is considered difficult to propagate. Cuttings from bisexual or female trees can be treated with IBA rooting hormone and planted mid-spring in a polythene tunnel with water misting. Seed should be soaked in hot water for 10 minutes followed by soaking in tap water for 48 hours before planting. While some sources recommend germinating the seed in a forestry seedling tube, the taproot is delicate and transplanting must be done with care. In-ground planting with protection for the young seedling from intense sun might be as successful.
Uses: Ornamental, edible seedpods, shade tree. The dried pods are naturally sweet and can be eaten raw by carefully biting around, and spitting out, the hard seeds. The dried pods, without the hard seeds, are ground into a sweet, chocolate tasting, caffeine free powder. The powder is nutritious, low fat, and has no bitter flavor components. The seeds are processed into an edible gum used as a thickener called locust bean gum. The whole pods with seeds can also be ground into a nutritious flour.

Comments

The seed pods are often used for animal fodder.
In ancient times, the carob seed was used to measure weight because of its uniformity. The word carat, a unit of weight, comes from the same Greek word as carob. Because a pure gold Roman coin, the Solidus, weighed 24 seeds, the carat also became used to define the purity of gold, with 24 carat being pure.
Carob is distantly related to other Legume family members with edible bean pods or filling, such as Guamuchil, Pacay, and Tamarind.


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Carob Tree: Ceratonia siliqua flowers male-female
Ceratonia siliqua flowers – male and female

Carob Tree: Ceratonia siliqua - pods

Carob Tree: Ceratonia siliqua - leaves

Carob Tree: Ceratonia siliqua


Latest update: December, 2023
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