Jaeger came from a well-known and highly-educated family, and was the grandson of Johann Heinrich Pestalozzi, founder of the Swiss public school system. As a young man Jaeger took a job in a wine warehouse on Lake Geneva in Switzerland and then emigrated to the United States. In 1865, he settled east of Neosho, Missouri in the Monark Springs area of Newton County. The following year he and his brother, John, planted a vineyard and became grape growers and wine makers.
Intelligent and proficient in several languages, Hermann Jaeger worked to breed new varieties of grapes, many of which came from wild Ozarks grapes - grapes commonly called "possum grapes". He also communicated with other grape experts around the world, sharing information about his work and learning from the works of others. He also wrote articles for scientific and grape journals, explaining the mysteries of grapes and his work on his farm.
In the 1870s, when the vineyards of France, Spain, and Portugal were struck by the deadly phylloxera louse, a call went out around the world to find grapes that were resistant to the disease. Encouraged by Missouri’s state entomologist, Charles Riley and after some testing, it was determined that grapes bred by Jaeger were resistant to the louse. His work proved to be a savior for the great vineyards of Europe. Working with other scholars and grape growers, Jaeger supplied cuttings from his Monark Springs vineyards to help replant those lost in Europe. In 1893, for his contribution to the grape and wine industries of France, Jaeger was awarded the coveted French Legion of Honour, the highest award that that nation can bestow on a civilian. He also made a lasting contribution to viticulture through his selection Jaeger 70, which is an ancestor of many of today's hybrid grapes.
In May 1895, Hermann Jaeger left his rural home, leaving a note instructing his family not to look for him. He disappeared and was never heard from again. His death is truly one of the great true mysteries of the Ozarks. The home which John Jaeger built still stands. Several members of the Jaeger family are buried on the old farm or on land which once was home to Hermann Jaeger, a world famous grape grower and nurseryman.