Harold Olmo studied horticulture at the University of California, Berkeley, where he earned his doctorate in plant genetics.

In 1948, he traveled a total of 12,000 miles in Iran, Iraq, Turkmenistan, Afghanistan and Pakistan to collect seeds and cuttings from the region.

[1] He also imported cuttings of the Greek varieties assyrtiko and moschofilero in the USA, which were stored at UC Davies until the Abbey of New Clairvaux started cultivating them in 2011.

[4][3] Over the course of his nearly 50-year career, Olmo also developed more than 30 new grape varieties, including Ruby Cabernet, Carnelian, Rubired and Royalty.

The sum of his work and research is stored at UC Davis, under the file collection number D280, and was digitized for global access in 2020.