Pistachios are native to northeastern Iran, Central Asia, and Afghanistan, where they’ve grown wild for thousands of years. Today, though, the United States dominates global production, growing about 65% of the world’s supply, nearly all of it in California’s San Joaquin Valley.
The Wild Origins of Pistachios
The pistachio tree, Pistacia vera, originated in a band stretching from northeastern Iran through Central Asia. Wild pistachio trees still grow across Afghanistan, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. Ancient peoples in these regions gathered and traded the nuts long before anyone planted them deliberately, and the pistachio eventually spread westward through the Middle East and into the Mediterranean.
Iran remained the center of pistachio culture for centuries. It’s where the dominant American variety, Kerman, gets its name. A plant explorer named Whitehouse collected the original seed from the city of Kerman in Persia (now Iran) and brought it to California, where it became the foundation of an entire industry.
Where Pistachios Grow Today
The United States is now the world’s largest pistachio producer by a wide margin. USDA projections for the 2025/2026 season put U.S. production at roughly 713,000 metric tons, accounting for 65% of global output. Iran comes in second at around 200,000 metric tons (18%), followed by Turkey at 120,000 metric tons (11%).
Within the U.S., about 95% of pistachios come from the southern San Joaquin Valley in California, roughly from Merced south. The region’s combination of scorching dry summers and cold winters is almost perfectly suited to what pistachio trees need. The first experimental plantings in California happened near Terra Bella in 1927, but commercial-scale orchards didn’t take off until the Kerman and Peters varieties were planted in the late 1960s. California’s first real commercial harvest came in 1976: 1.5 million pounds from 4,500 acres. Production has exploded since then.
What Pistachio Trees Need to Thrive
Pistachio trees are surprisingly specific about their climate. They need hot, dry summers with temperatures regularly exceeding 100°F to ripen their nuts properly. But they also require genuine winter cold, with temperatures dropping below 45°F for enough hours to trigger the next season’s growth cycle. Temperatures below 15°F, however, can damage the trees. This narrow sweet spot of extreme summer heat and moderate winter cold explains why so few regions can grow them commercially.
The trees prefer light, well-draining sandy loam soil with high calcium content. Unlike many fruit and nut trees, pistachios actually tolerate salty soil, which gives them an advantage in arid agricultural regions where salt buildup is a common problem.
How Pistachio Trees Produce Nuts
Pistachio trees are dioecious, meaning each tree is either male or female. Only female trees produce nuts, but they need pollen from a male tree to do it. Wind carries the pollen from male to female trees, so commercial orchards plant them in a specific ratio: typically one male tree for every 8 to 11 females. In California, nearly every orchard pairs the female Kerman variety with the male Peters variety as its pollinator. Kerman accounts for 99% of California’s pistachio production thanks to its large size, crisp texture, and reliably split shells.
Patience is a real cost of pistachio farming. Trees have a long juvenile period, producing few nuts before they’re five years old and not reaching full bearing capacity until 10 to 12 years of age. That’s a decade of investment before an orchard hits its stride.
Harvest Season and Processing
Pistachios ripen through late August and September. As the nut matures, the shell splits along its long seam (that familiar crack you pry open with your fingernails), and the fleshy outer hull begins to separate from the shell. Growers watch for the hull to change color to red, which signals that the nuts are ready. Delaying harvest until the maximum number of nuts have split shells improves the overall quality of the crop.
Once harvested, the outer hull needs to be removed within 24 hours. Waiting longer causes the hull to stain the shell, turning it blotchy or dark. After hulling, nuts are sorted: split shells go one direction (these become the snacking pistachios you buy), unsplit shells go another, and blank shells with no seed inside are discarded. Any nuts with black discoloration are thrown out because they can harbor toxic mold.
Water and Environmental Cost
Pistachio orchards are thirsty. Research from UC Davis tracking a pistachio orchard in Madera County, California found that producing one ton of pistachios requires roughly 2.3 to 2.5 acre-feet of water, the vast majority of it from irrigation rather than rainfall. That works out to about 375 to 400 gallons per pound of pistachios. In a state that regularly faces drought, the water demands of California’s rapidly expanding pistachio acreage are a growing point of tension. Pistachios aren’t unique in this regard (almonds and walnuts have similar footprints), but the scale of new plantings keeps water use in the conversation.