Peter Jonas Bergius was born in 1730 in the parish of Hvittaryd, Kronoberg, the youngest of seven children. The parents died early and his brother Bengt and other guardians took on the responsibility for the family. In 1746 Peter Jonas began his studies at Visingsö Kongl. Trivialskola och Gymnasium. At the age of 16 he registered at Lund University and obtained a degree in theology. Not until several years later did he begin the studies that would influence his entire career.
On the advice of his brother Bengt he became a medical student and moved to Uppsala in order to study medicine and botany with Linnaeus and Nils Rosén. (At the time, natural history - not least botany - was often coupled with medicine.) He became a dedicated pupil at Linnaeus's private and public lectures. Commissioned by Linnaeus, Bergius later went to Gotland to gather plants, fossils and corals for C.G. Tessin's collection of natural-history specimens.
His medical training ended in 1755 with a disputation on a thesis about smallpox. Peter Jonas then moved to Stockholm and started a medical practice. There was a great shortage of doctors and he worked hard to provide medical care also for the poor. His work soon attracted attention from the Collegii Medici – later the Medical Board (now the National board of Health and Welfare) and rumours spread rapidly about the excellent doctor. In 1758 he was elected a member of the Royal Academy of Sciences and became chairman three times. He wrote several books and other publications on medicinal herbs, inoculation against smallpox, states of illness, botany, etc. The most important are perhaps Materia medica, Plantae capenses and Tal om fruktträdgårdar [A Discourse on Orchards].
Bergielund
The success of Peter Jonas Bergius made him a rich man, and in 1759 Bergielund was acquired as a summer residence. During the time in Uppsala he had missed his brother a lot, but in Stockholm they were reunited and lived together sharing the expenses at Bergielund and in the city.
When the Collegii Medici was to appoint a chair in 1761, Peter Jonas was elected as professor of natural history and pharmacology. His membership of the Royal Society in London should also be mentioned as one of his merits, since he is one of the few Swedes who have been paid this honour.
In 1777 Bergielund was enlarged to 7 hectares and could be thoroughly developed. Peter Jonas was responsible for the garden and the herbarium, while Bengt built up the fine collection of books. Both the book collection and the herbarium are still extant, while the garden nowadays is situated at Frescati. Bergielund was the great commitment of Peter Jonas right up to his death in 1790.