A postman working the scorching California heat in the late 1920s planted a few seeds in his modest La Habra Heights garden, hoping to grow decent avocados. What sprouted was not just better fruit—it was a genetic lottery winner that would alter the trajectory of global agriculture, feed billions of people, and create an industry worth over $20 billion today. Yet the man who discovered it never saw a fraction of that fortune. This is the story of Rudolf Hass, the Milwaukee-born mailman whose humble backyard experiment became the most consequential fruit mutation in modern history.
A Postman’s Side Venture
Rudolf Hass arrived in California in 1923, having quit school at fifteen and later marrying at twenty-seven. Working jobs as a salesman and mail carrier, he gradually saved enough to purchase a small avocado grove in the hillside community east of Los Angeles. In the late 1920s, he purchased seedling trees from A. R. Rideout of Whittier, intending to develop budded trees of the Lyon variety across two acres.
The plan was modest, practical, and entirely unremarkable. What would unfold, however, belonged to the realm of accident and serendipity.
Hass’s children first brought a particular tree to his attention, preferring its fruit to the others growing in the grove. When he examined it more closely, he noticed something striking. The fruit was creamier, richer, and more robust than the Fuerte variety—the industry standard at the time. The tree itself was vigorous and productive. Where other avocado growers saw marginal improvements, Hass recognised something exceptional.
The Stroke of Fortune
In the pre-war years, most American avocados came from the smooth-skinned Fuerte tree. It was the measuring stick against which all others were compared. The Hass fruit differed so dramatically from the Fuerte that some in the industry initially resisted it. But Hass was convinced. He decided to stake his modest enterprise on this unexpected discovery.
In August 1935, Hass patented his avocado tree, receiving Plant Patent No. 139—the first patent ever granted to a producing fruit tree in the United States. For a moment, fortune seemed to smile upon him. He had created something new, something protected by law. The future appeared bright.
The Business Deal That Never Paid Off
Hass understood he could not manage the growing and selling alone. He entered into an agreement with Harold Brokaw, a Whittier nurseryman, to grow and promote the variety. Under their arrangement, Hass was to receive 25% of the proceeds from tree sales. It seemed a reasonable partnership. Brokaw would handle distribution; Hass would receive his share.
Brokaw proved an effective promoter. He began propagating the Hass variety exclusively and promoting it in favour of the then standard varieties, eventually achieving yearly sellouts of his nursery crops, selling between 3,000 and 10,000 trees annually. The demand was genuine. Nurseries across California wanted the tree. Growers could see what Hass had seen: this avocado was superior.
Yet there was a fatal problem.
A Patent Violated, A Fortune Lost
Patent protection in 1935 sounded like ironclad security. In practice, it proved fragile against determined growers. Unscrupulous growers purchased single trees from Brokaw, then illegally propagated additional trees through budwood grafting from that original purchase. Once a grower had one legitimate Hass tree, they could multiply it across their entire orchard without paying Hass a cent.
The violation was widespread and nearly impossible to police. Hass pursued enforcement, but the sheer scale of the theft overwhelmed legal remedies. Hass made less than $5,000 in royalties over the life of the patent during its 17-year term. Five thousand dollars. For changing the world’s fruit supply.
His patent expired in 1952—the same year he died—and it could not be renewed. By then, the Hass avocado was everywhere. But Rudolph Hass would never see the industry his discovery had created.
The Quiet Revolution No One Thanked Him For
What happened next was quietly extraordinary. The Hass avocado spread across California, then across North America, then across the globe. Today, 95% of all avocados consumed in the United States, as well as a majority of avocados consumed globally, can be traced back to his tree.
In the United States, the Hass variety now accounts for 80% of the national avocado crop and 95% of California’s production. The dark-green, pebbly-skinned fruit became the standard against which all others are measured. When consumers think of avocado—whether sliced on toast, blended into smoothies, or mashed into guacamole—they are thinking of Hass’s accidental discovery.
The industry it created is staggering. In 2025, the global avocado market reached a value of nearly USD 19.81 billion, with projections to grow at a compound annual growth rate of 9.20% through 2035, potentially reaching USD 47.77 billion by the end of the decade. Twenty billion dollars generated from a tree a postman planted in his backyard nearly a century ago.
A Legacy Written in Fruit, Not Fortune
The original tree Hass planted lived for 75 years before being felled in 2002, and a plaque now marks the spot where it grew. Visitors to La Habra Heights can stand where history quietly happened—where a man tending his small grove had no idea he was reshaping global agriculture.
Rudolph Hass never became wealthy. He never saw the avocado toast craze that would define millennial dining. He never witnessed the fruit he discovered become a supermarket staple in countries he would never visit. The industry built upon his work has generated tens of billions whilst his own financial reward amounted to modest royalties that dried up when his patent expired.
Yet his name endures in every Hass avocado sold worldwide. From supermarket shelves to restaurant menus to home kitchens across Australia and beyond, his discovery remains. It is the peculiar immortality of invention—the man forgotten whilst his creation feeds the world.