The pistachio is a relative of both the cashew and the mango. It is deciduous (drops its leaves each year) and dioecious (comes in separate sexes and both a male and a female tree are needed to produce edible nuts). The trees are wind-pollinated rather than bee-pollinated, with the male trees bearing pollen and the female trees bearing the nuts. Like many other nut trees, the pistachio is alternate bearing — producing a heavy crop one year and a lighter crop the next.

Pistachios mature rather slowly, reaching significant production a full seven to ten years after planting. Peak production, it is believed, is reached at about 20 years.

Climate also plays a role in pistachio production. Too mild a winter, or heavy rainfall during the pollination period, can reduce yield. Pistachio trees require approximately 1,000 hours of temperatures at 45 degrees F. or below to bring about the dormancy necessary for good production.

California pistachios are grown on various rootstocks. The Kerman variety is budded to the rootstock when the rootstock is one year old. These rootstocks were developed to achieve a healthier and more vigorous plant.

While pistachios have been grown in Europe, Asia and the Middle East for centuries, they have only been a commercial crop in the United States since 1976, when California harvested its first crop. Today, the Kerman variety is the tree of choice for almost all California pistachio growers. There are only minimal plantings of other varieties. The Kerman variety was chosen for its larger nuts and widely split shells.