Discover the rich history of walnuts and explore the varieties grown around the globe.
From ancient Persia to modern California — a journey through time.
The walnut's story begins in the fertile lands of Central Asia and the Middle East, where archaeological evidence suggests humans were gathering and eating walnuts as far back as 9000 BC. The English or Persian walnut (Juglans regia) is believed to have originated in the region stretching from Iran and Iraq through to the Himalayas.
The ancient Persians revered the walnut and were among the first to cultivate it systematically. Trade routes carried walnuts westward through the ancient world, and by the time of the Greeks and Romans, the walnut was well established throughout the Mediterranean. The Romans — who called it "Jovis glans" (Jupiter's acorn) — spread cultivation across their empire, including into Britain, which is thought to be one reason the common variety is still called the "English walnut" in North America today.
Through the Middle Ages, walnuts remained a staple food and trade good across Europe and the Islamic world. Medieval physicians prescribed walnut kernels for headaches and brain ailments, drawing on the ancient Doctrine of Signatures — the idea that a plant's shape hints at its medicinal use, and the walnut kernel unmistakably resembles a human brain.
By the Renaissance, walnut oil had found its way into artists' studios across Europe. Leonardo da Vinci is documented to have used walnut oil as a paint medium, prizing its slow drying time and resistance to yellowing. The hard, richly grained walnut wood also became a favourite of furniture makers and craftsmen during this era.
North America has its own native walnut species — the Black Walnut (Juglans nigra) — which indigenous peoples had long used for food, medicine, and as a dark brown dye. European settlers brought the English walnut with them, and over time California emerged as the world's premier walnut-growing region, blessed with the warm days, cool nights, and well-drained soils that walnut trees love.
Today, California produces roughly 99% of US commercial walnuts and is the world's largest exporter of the nut, shipping to markets in Europe, Asia, and beyond. The global walnut industry is worth billions of dollars, and the nut continues to grow in popularity as consumers seek out its well-documented health benefits.
The four main types of walnut grown and cherished around the world.
Juglans regia — the walnut you find in virtually every supermarket. Despite being called "English," it originated in Persia (modern Iran). It has a thin, smooth shell and a mild, creamy flavour. California's entire commercial industry is built on cultivars of this species.
Juglans nigra — native to the forests of eastern North America. The shell is exceptionally hard and thick, but the kernel inside has a bold, rich, earthy flavour that is highly prized in specialty baking and confectionery. The husks produce a dark brown dye used in crafts and historically in hair colouring.
Juglans cinerea — also native to North America. The kernel has an unusually sweet, buttery taste, which gives the tree its common name. Butternut is unfortunately threatened by a fungal disease (Sirococcus clavigignenti-juglandacearum) that has devastated wild populations across its range.
Juglans ailantifolia var. cordiformis — a Japanese variety of walnut with a distinctive heart-shaped shell. The kernel cracks out whole easily, making it a favourite with nut lovers who prefer to shell by hand. It has a mild, sweet flavour and is increasingly grown in North America and Europe as a novelty and specialty crop.