Prunes are dried plums, but not just any plum. They come from specific varieties of European plum that have firm flesh and high sugar content, traits that allow the fruit to dry into a chewy, shelf-stable product without fermenting around the pit. The most widely used variety worldwide is the French prune, also called the Prune d’Agen, a small purple-skinned plum originally cultivated in southwestern France.
Why Only Certain Plums Become Prunes
There are hundreds of plum varieties, but only a handful work for drying. The key distinction is sugar content and flesh density. European plums from the species Prunus domestica tend to have firm, dense flesh with enough natural sugar (often 20% or higher) to preserve well during drying. Juicier varieties, like the round Japanese plums you’d find in a grocery store’s fresh fruit section, contain too much water and not enough sugar to dry properly.
The classic prune plum is the Prune d’Agen, a small oval fruit with deep blue-purple skin and golden-green flesh. It remains the dominant variety in both France and California. Newer cultivars have been developed to improve on it. The University of California, Davis, for instance, bred a variety called Sutter by crossing a Sugar plum with a French cultivar. Sutter ripens about 10 days earlier than the traditional French prune and dries into what breeders describe as a dense, fine-textured prune with complex fruity flavor. Breeding programs like this focus on extending the harvest window and improving dried quality rather than changing the fundamental characteristics of the fruit.
From France to California
The prune industry traces back centuries to the Agen region of southwestern France, where the warm, dry climate proved ideal for growing and sun-drying plums. French prunes became a major trade commodity across Europe, and the Agen name became so closely tied to the product that, since 2002, “Pruneaux d’Agen” has been a Protected Geographical Indication in the European Union, meaning only prunes grown and processed in that region can carry the label.
California’s prune industry has a specific origin story. A French immigrant named Louis Pellier arrived in California during the Gold Rush in 1849. He established a nursery called City Gardens in San Jose in October 1850, and during the winter of 1856-57, his brothers Pierre and Jean brought cuttings of la petite prune d’Agen from France. Those rootstocks thrived in the Santa Clara Valley’s Mediterranean climate, and within a few decades, California had become one of the largest prune-producing regions in the world. Today, nearly all U.S. prunes come from California’s Central Valley, particularly the Sacramento and San Joaquin Valleys.
Where Prunes Are Grown Today
The global prune market is dominated by a few key players. California and France are the two largest producers of dried prunes specifically, and they compete head-to-head in European markets. France supplies more than half the EU prune market, while the United States accounts for roughly a third. The French industry has positioned itself around large-grade, premium prunes, while California’s exports lean more toward pitted prunes for convenience.
Chile and Argentina are also significant producers. Chilean plums are grown in large volumes (nearly 425,000 tonnes of plums and related fruits in 2022), though much of that production goes to lower-grade dried product. Argentina’s prunes largely serve the processing industry rather than retail. Other countries with substantial plum harvests include China (by far the world’s largest plum grower at over 6.7 million tonnes), Romania, Serbia, and Turkey, though much of their crop is eaten fresh or used for other products like jam and brandy rather than dried into prunes.
How Fresh Plums Become Prunes
The transformation from plum to prune is straightforward but precise. Fresh prune plums are about 75% water. The drying process brings that moisture content down to roughly 18-19%, which is low enough to prevent spoilage but high enough to keep the fruit pliable.
Commercially, most prunes are dried in large tunnel or cabinet dryers rather than in the sun. Conventional drying uses air heated to around 165-175°F, and the process takes 25 to 28 hours. The fruit temperature itself is kept at or below 165°F to avoid cooking the exterior before the interior has dried. Newer parallel-flow systems push initial air temperatures up to 195-200°F and can finish drying in 11 to 16 hours, cutting production time nearly in half while achieving similar moisture levels.
After drying, prunes are typically stored in bins and later rehydrated slightly with steam before packaging, which gives them the glossy, sticky texture consumers expect. Some producers also pit the prunes mechanically at this stage. The entire process, from harvest to packaged product, usually happens within the same growing region, keeping production tightly linked to the orchards where the plums are picked.
The Plum-to-Prune Naming Shift
If you’ve noticed “dried plums” appearing on packaging where “prunes” used to be, that’s no accident. In 2000, the U.S. Food and Drug Administration approved a petition from the California Dried Plum Board to allow “dried plums” as an alternative label. The industry pushed for the change because consumer research showed that younger shoppers associated the word “prune” with old age and digestive trouble, while “dried plum” sounded like a normal snack. Both terms refer to the same product, and you’ll still see “prunes” used widely outside the U.S. and on many domestic brands.