Elizabeth (née Smith), John's stepmother, brought the children to Pennsylvania after the family was ransomed by relatives from Philadelphia.

Later, he made contact with European botanists and gardeners interested in North American plants, and developed his hobby into a thriving business.

In 1737 Bartram travelled by horseback through modern day Delaware and the Eastern Shore of Maryland to Northampton County, Virginia.

In the fall of 1738, he made another excurion from his home in Philadelphia through Virginia, visiting the Gover family in Anne Arundel County, to Port Tobacco on the Potomac.

[8] In 1743, he visited western parts of New York and the northern shores of Lake Ontario, and wrote Observations on the Inhabitants, Climate, Soil, Rivers, Productions, Animals, and other Matters Worthy of Notice, made by Mr. John Bartram in his Travels from Pennsylvania to Onondaga, Oswego, and the Lake Ontario, in Canada (London, 1751).

During the winter of 1765/66, he visited East Florida in the south, which was a British colony, and published an account of this trip with his journal (London, 1766).

[11] About 1728, he established an 8-acre (32,000 m2) botanic garden in Kingsessing, on the west bank of the Schuylkill, about 3 miles (5 km) from the center of Philadelphia, Pennsylvania.

[12] Bartram was particularly instrumental in sending seeds from the New World to European gardeners; many North American trees and flowers were first introduced into cultivation in Europe by this route.

Collinson, also a lover of plants, was a fellow Quaker and a member of the Royal Society, with a familiar relationship with its president, Sir Hans Sloane.

Earl Petre's death in 1743 resulted in his American tree collection being auctioned off to Woburn, Goodwood, and other large English country estates.

The boxes generally contained 100 or more varieties of seeds, and sometimes included dried plant specimens and natural history curiosities, as well.

In 1765, after lobbying by Collinson and Benjamin Franklin in London, George III rewarded Bartram a pension of £50 per year as King's Botanist for North America, a post he held until his death.

He is best known today for the discovery and introduction of a wide range of North American flowering trees and shrubs, including kalmia, rhododendron, and magnolia species; for introducing the Dionaea muscipula or Venus flytrap to cultivation; and for discovering the Franklin tree, Franklinia alatamaha in southeastern Georgia in 1765, later named by his son William Bartram.

He wrote Travels Through North & South Carolina, Georgia, East & West Florida,... which was published in Philadelphia by James & Johnson in 1791.