Carob Ceratonia Siliqua L

Species description Carob is a spreading tree with a broad, semi- spherical crown. The sturdy trunks and branches have rough, grey-brown bark. The leaves are alternate and pinnate, at times with a terminal leaflet. Carob trees are generally dioecious, meaning that male and female flowers are produced on different trees. Only female trees will produce pods, but they need male trees for effective pollination. Carob trees flower in autumn; numerous, small, catkins are born on spurs of old wood, and arranged in a spiral along the floral axis. They are both wind and insect pollinated. The elongated, leguminous pods may be straight or curved and take one year to develop. The ripe pods eventually fall to the ground, from September to November.

Natural and cultural history Carob’s wild relative, Ceratonia oreothaum, is native to the Mediterranean region. Romans in the eastern Mediterranean basin are thought to have first domesticated carob trees. Carob was grown throughout the Mediterranean, with cultivation peaking during the early Islamic period (approx. 600 CE).

Planting considerations and propagation techniques Carob trees may grow to 25 feet tall with a canopy 25 feet in diameter. Carob trees are adapted to a mild Mediterranean climate, and they are cold tolerant to around 20ºF. They take 6-7 years to produce the first seed crop, and can live for a century or more. Though carob trees are generally either male or female, limbs of male trees may be grafted onto female trees, and hermaphrodite trees are also available. Choose sunny areas with adequate spacing; carobs need about 30 feet between trees for full development. Carob trees can withstand a wide range of soil types and are tolerant of rocky, soils, and saline soils. Carob root mycorrhiza fix nitrogen and make it available for other nearby plants. They do not grow well on poorly drained soils. Propagate carob trees using seed and grafting. The seeds will germinate easily when fresh, but require scarification when dried. Young seedlings are very frost sensitive. Cuttings are difficult to root, and grafting onto seedling rootstock is a common practice for propagating cultivars.

Water needs Carob trees are adapted to arid regions and are very drought tolerant. Once established, they can grow without supplemental irrigation in areas receiving 10-20 or more inches of rainfall per year, with 15 or so inches required for fruit-set. The tree will produce higher yields with more than 20 inches of rainfall.

Care Mature trees may require a light pruning to remove dead or diseased and damaged wood every 3-4 years.

Harvesting and processing Carob pods are used as a dark, naturally sweet, rich and flavorful chocolate substitute. The pods are ground or pounded into a fine powder, which is added to cold or heated milk for drinking or used in baking, syrups and beverages. The carob beans were at one time used for the carat weight unit for weighing gemstones.

References and resources Bonner, Franklin T. 2008. The Woody Plant Seed Manual. No. 727. Government Printing Office. Dunmire, W. W. 2004. Gardens of New Spain: How Mediterranean Plants and Foods Changed America. University of Texas Press, Austin, TX. Haq, N. 2008. Ceratonia siliqua, carob, pp. 387-391. Eds. Janick, J. and R.E. Paull. The Encyclopedia of Fruit and Nuts. CABI Publishing, Cambridge, MA. HortPurdue. 2015. Carob: Ceratonia siliqua. https://www.hort.purdue.edu/newcrop/morton/carob.html. Morton, J. 1987. Carob. p. 65–69. Julia F. Morton. Fruits of Warm Climates. JF Morton. Miami, FL. Available online through: Center for New Crops & Plant Products, Purdue University, West Lafayette, IN. https://www.hort.purdue.edu/newcrop/morton/carob.html. Plants for a Future (PFAF). n.d. Ceratonia siliqua -L. http://www.pfaf.org/user/Plant.aspx?LatinName=Ceratonia+siliqua