The almond tree (Prunus dulcis) is a deciduous tree cultivated for thousands of years for its nutritious edible seeds, known as almonds, and beautiful blossoms.
Botanical Identity and Physical Characteristics
The almond tree belongs to the Prunus genus (Rosaceae family), making it a relative of peaches, cherries, and apricots. It is classified in the subgenus Amygdalus, distinguished by the corrugated shell surrounding its seed. These trees typically grow 10 to 15 feet (3 to 4.5 meters) tall, though some reach 30 feet (9.1 meters).
The bark of younger almond trees is smooth and gray, becoming darker and more fissured with age. Its leaves are light green, elongated, and narrow, measuring 3 to 5 inches (8 to 13 cm) long with serrated edges. In early spring, often before leaves emerge, the tree produces fragrant, five-petaled flowers ranging from white to pale pink, usually 1 to 2 inches (3 to 5 cm) in diameter.
Botanically, the “almond” is not a true nut but a drupe—a fleshy fruit with a hard inner layer enclosing the seed, similar to a peach or cherry. The almond fruit measures 1.4 to 2.4 inches (3.5 to 6 cm) long and consists of an outer, leathery, greenish-gray hull. Inside this hull is a hard, woody shell, and within the shell lies the edible kernel.
Ideal Growing Conditions
Almond trees thrive in Mediterranean-like climates, characterized by mild, wet winters and hot, dry summers. This climate provides adequate sunlight for growth and productivity. For healthy flowering and fruit development, almond trees require winter dormancy, accumulating 250 to 500 “chill hours” below 45°F (7°C).
Despite needing winter chill, almond trees are susceptible to frost damage, especially during early spring bloom. Temperatures below 27°F (-2.8°C) for 30 minutes during bloom can cause significant crop loss. Optimal soil conditions include well-drained, deep loamy or sandy loam soils with a pH between 6.0 and 7.5, preventing waterlogging and yield reduction.
The Almond Production Cycle
The annual almond production cycle begins in late winter or early spring with blossoms, typically from February to March in the Northern Hemisphere. Most almond varieties are self-incompatible, requiring cross-pollination from a different variety to produce fruit. This process relies on insect pollinators, primarily honey bees, for transferring pollen between varieties in an orchard. A single almond blossom may need multiple bee visits for successful fertilization.
After pollination, small green fruits develop, with the kernel growing inside its protective shell and fuzzy outer hull. This growth continues through spring and early summer. As the fruit matures, the outer hull splits open, signaling the kernel is drying and nearing maturity. This hull split typically occurs in July in the Northern Hemisphere.
Harvest usually takes place from mid-August to October, after hulls have fully split and almonds have dried on the tree. Mechanical shakers dislodge the almonds, which fall to the ground and are collected. The almonds, still in their shells, are then left to dry naturally in the sun for 7 to 10 days before further processing.
Common Varieties and Their Applications
Almond cultivation includes numerous varieties, with about 30 types grown in California, a major global producer. These varieties are categorized by characteristics like size and shape. Common classifications include Nonpareil, California, and Mission. Nonpareil almonds are widely used due to their thin shells and smooth kernels, making them easy to blanch and process. Mission almonds have harder shells and darker, wrinkled kernels, well-suited for roasting and retaining seasonings.
Almonds are broadly classified into sweet and bitter types. Sweet almonds are commonly consumed and found in supermarkets for their mild, nutty flavor. They are a versatile ingredient, used in baking, confectionery, as snacks, and to produce almond milk and oil. Bitter almonds contain amygdalin, which converts into hydrogen cyanide when ingested, making them toxic if consumed raw in significant quantities. While not sold for raw consumption, bitter almonds are used in small, processed amounts for flavorings and extracts, where toxins are removed or neutralized.