How to grow and care for a carob tree

The carob tree (Ceratonia siliqua), also known as the locust bean tree, is a perennial tree native to the Mediterranean, where it has been cultivated for centuries. It has attractive, leathery, dark-green evergreen leaves, small scented flowers and edible pods.

Carob seeds are so consistently similar in weight that they became a standard measure of weight for precious items such as jewels and gold. If a jewel balanced the scales with five carob seeds on the other side, it was said to weigh ‘5 carobs’, which became ‘5 carats’. This figure is still used today, with one carat equal to 200 milligrams.

How to grow a carob tree

A carob tree needs a spot in full sun with free-draining soil. Carob trees can grow in a variety of soil types, including sandy or loamy soils, as long as they're not waterlogged. They are likely to require regular watering, especially during dry periods, to establish strong root systems.

Once established, carob trees can tolerate drought conditions. Boost this by applying a layer of organic mulch around the base of the tree to retain moisture and suppress weeds. Fertilise the tree annually with a balanced organic fertiliser, to promote healthy growth.

What is carob?

Like many of its cousins in the bean family, the carob tree produces elongated, green pods, which turn brown as they ripen. These pods are the main source of its culinary and commercial value. They contain a nutritious, sweet pulp (rich in fibre, and essential minerals such as calcium and potassium). This can be dried and ground into a fine powder called carob powder, which serves as a natural alternative to cocoa powder and is used in culinary applications such as baking, beverages and confectionery.

Carob syrup, another valuable product derived from the pods, is a thick, sweet syrup that resembles molasses in taste and consistency. It's often used as a natural sweetener and flavouring agent in desserts, beverages and sauces. Both the syrup and the powder have a mildly sweet and nutty flavour, making them a popular snack in some regions and cuisines.

Can a carob tree grow in the UK?

Growing a carob tree in a UK garden can be a rewarding experience and, while traditionally associated with warm climates, they can thrive in the UK under the right conditions. They are hardy and adaptable, making them an excellent choice for gardeners looking to add a unique, versatile and useful tree to their garden. However, they can also be grown in pots and make an excellent conservatory tree. Hardy down to -5ºC, they may need frost protection in colder areas, or grow them in pots and overwinter them indoors.

Size, height and spread

A carob tree can reach a height of up to 12m and a potential spread of 8m, but it can also be grown in a container and kept to a much more manageable size.

Value to wildlife

The flowers of the carob tree are small and inconspicuous, but they produce a sweet and pleasant fragrance that attracts pollinating insects such as bees. Along with wind, these pollinators help to fertilise the flowers, ensuring a good crop of carob pods. Carob pods serve as a source of food for various animals, including birds and mammals.

Where to grow a carob tree

Plant your carob tree in full sun. This tree needs free-draining soil and will not thrive in acidic soil or sites that get waterlogged.

The carob tree is hardy only in mild regions of the UK, so will need shelter or frost protection. They are slow-growing trees, so could be grown in pots in the conservatory.

How to plant a carob tree

To plant a carob tree, dig a hole that is deep and wide enough to accommodate the tree's rootball. Place the tree in the hole, ensuring that the top of the rootball is level with or slightly above the soil surface. Backfill the hole with soil, firming it gently around the roots.

Water the tree thoroughly after planting to settle the soil and encourage root establishment.

How to prune a carob tree

Pruning is best done during late winter or early spring. Remove any dead, damaged or crossing branches to improve airflow and maintain an open canopy. This will help prevent diseases and promote the tree's overall health.

Additionally, prune to shape the tree and control its size if necessary. Use clean and sharp pruning tools to make clean cuts and minimise the risk of disease transmission.

How to propagate a carob tree

The easiest way to propagate a carob tree is by growing it from seed. Scarify the hard seed coat by nicking or sanding it lightly to improve germination rates. Soak the seeds in water for 24 hours before planting them in a free-draining potting mix. Keep the soil consistently moist, and provide warmth and sunlight for germination.

Pests and diseases

While carob trees are generally hardy and resistant to most pests and diseases, they can occasionally be affected by aphids, scale insects and root rot. Monitor the tree regularly for any signs of infestation or disease, such as distorted leaves, sticky residue and wilting.

Remove and destroy any diseased or affected plant material to prevent further issues and ensure proper drainage to prevent root rot.