Unearthing the Roots of the Past

Archaeology at Historic Bartram's Garden

By: Alexandria Mitchem

Originally Published in 2020

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ESTABLISHED around 1728, Bartram’s Garden is the oldest surviving botanical garden in the United States. John Bartram (1699–1777) was a Quaker farmer who became a self-trained botanist and naturalist. He and his son William (1739–1823) undertook numerous natural collection journeys along the east coast of the American colonies and later the United States of America. Three generations of the Bartram family cultivated these native North American plants in their Philadelphia home. Through contacts with merchants in London, the Bartrams ran a profitable seed and plant clipping business, as plant species grown in their garden were considered “exotic and desirable” by European landscapers, collectors, and scientists. They went on to sell plant clippings, including hybrid flowers, to Americans and eventually opened their garden for public visitation.

Aerial view of the house at Batram's Gardens.
The Bartram family home, built in 1731, and its associated Ann Bartram Carr garden viewed from above. Drone image by Jason Herrmann.

The Bartram House and other buildings are located on a natural terrace 40 to 50 feet above the Schuylkill River. The gardens extend down to the river’s edge. After the American Revolution and John Bartram’s death, his sons John Bartram Jr. (1743–1812) and William Bartram continued the international trade in plants and expanded the garden and nursery business. After 1812, Anne Bartram Carr (1779–1858), daughter of John Jr., and her husband Robert Carr (1788–1866) ran the garden. They continued to expand commercial interests in cuttings from North America for both an international and domestic audience. Over time the family added onto the buildings and gardens on the property. In 1850, following financial hardships, the Carrs sold the farm and garden to Andrew Eastwick (1811–1879), who used it as a private park for the estate he built on an adjoining property. The Bartram property was then bought by the city of Philadelphia in 1891, and the John Bartram Association was founded in 1893. The park is now jointly managed by the Association and by the Philadelphia Department of Parks and Recreation as a museum, archive, and botanical garden. Several trees dating to the Bartrams’ original occupation of the site are still growing there, including gingko (Gingko biloba) and yellowwood (Cladrastis kentukea) trees. The garden’s famous franklinia (Franklinia alatamaha) is a descendent of the ones planted by William Bartram in the 1760s.

A drawing of the house and front garden at Bartram.
1758 “draught” or draft of the Bartram home and garden drawn by William Bartram. Image courtesy of Joel Fry, Bartram’s Garden.

Today, many people are interested in the historic layout and contents of Bartram’s Garden. Historians, archaeologists, botanists, and garden enthusiasts all conduct research in the gardens and are attracted to programming offered by the John Bartram Association. Understanding the various forms of the past gardens helps us to learn more about the way in which the natural landscape was used and improved for gardening activities, and how the Bartrams’ use of greenhouses and other technologies expanded their botanical repertoire even further.

Reconstructing the Garden

How do we know what Bartram’s Garden looked like in the 1700s and 1800s? One major source of evidence is archival documents. John Bartram designed his garden to reflect what was known as a wilderness garden.
This format bewildered those used to a more formal, European-style garden. Correspondence between the Bartrams and their colleagues and patrons reveal evidence about the layout and function of the garden. Joel T. Fry, the current curator at Bartram’s Garden, has attempted to identify the modern scientific names of the plants grown by the Bartrams that were listed in five known bills of sale and broadsides (seed catalogs) ranging from the mid-18th century through the early 19th century. While a start, this can be completed with only limited accuracy as use of the Linnaean taxonomic system had just begun. Many names in these records were colloquial or from different systems of botanical nomenclature and are not easily matched to plant names today.

There are two particularly helpful drawings of Bartram’s Garden. One is a 1758 drawing by William Bartram, which shows the house and the garden as it extends towards the river, overlaid by a grid of paths. The other was done by William Middleton Bartram (1838–1916), a descendant who lived in the vicinity of the garden. His depiction dates to somewhere around 1850. These sources of evidence provide valuable information about the layout of the garden at these times, including the location of buildings (sometimes labeled with their function) and pathways. However, to uncover aspects of the garden that were only partially represented in historical writings, or perhaps were not mentioned at all, archaeologists have also conducted excavations on the property.

Side of the house at Bartram showing the two floors, garden, and porch.
The side of the Bartram home that faces the Schuylkill River. On the left side of the image is the area where archaeologists looked for a study and found evidence of planting beds. The beds are recreated in the modern landscape.

Archaeological Definitions

ASSOCIATED ARTIFACTS: These are artifacts that archaeologists are sure were part of a single depositional event. These objects can be used to date the surrounding sediments.

FEATURES: Non-movable remains of past human activities, often indicated by different soil colors and textures.

TEST PITS: Small excavation units, often employed to figure out what kinds of features and artifacts are in an area before opening up a larger and more extensive excavation.

RESISTIVITY TESTING: Archaeologists use Soil Resistivity Testing to learn about sediment without excavation. By passing a small electrical current through the ground, they can determine pockets of different sediment, as its compactness and moisture content affect the current’s flow.

The house and part of the garden at Bartram.
A modern photo of the Bartram home and garden showing the paths. The groundskeepers reconstructed them to be straight, in keeping with evidence from the 1758 drawing and archaeological findings. Photos by Chantel White.

Garden Beds and Paths

Some of the most extensive archaeological information we have about the garden itself was found by archaeologists who were searching for other information around the property. William Bartram’s 1758 drawing includes a small, stand-alone building labeled “my Studey [sic].” Historians have long debated whether any of the known buildings may have already been present on the property when it was purchased by John Bartram. The architectural style of this small detached study suggests it was likely built by earlier Swedish settlers and then served several later purposes for the Bartram family, eventually being repurposed
as a study after the expansion of the main kitchen. At some point, this small building was destroyed or deconstructed, requiring archaeological excavation to learn more about its end. In 1980, a field school led by Penn anthropologist Dr. Robert Schuyler attempted to locate this building. Initially, they dug four separate excavation units but only found ambiguous traces of a structure.

These same excavation units led to the discovery of extensive and rich traces of a past garden. After clearing away recent soil, the team uncovered various garden features hidden below. These features, such
as planting beds and garden paths, were dated using associated artifacts and allowed the archaeologists
to envision the historic garden in more detail. The archaeological information also helped them to imagine the daily work that would have been needed for the garden’s construction and upkeep. The garden beds were deeply cultivated, up to four inches in some places, and the soil around them suggests that the area was carefully managed to provide level spots for planting. When these excavations took place in the 1980s, the paths through the garden were curved, not straight as they were depicted in the 1758 map. Archaeologists discovered traces of the original straight paths, and the John Bartram Association re-laid the modern pathways to reflect their original design, which visitors can walk today.

A small, round, man-made pond filled with lily pads and other pond plants.
The pond at Bartram’s Garden as it is reconstructed today. Photo by Chantel White.

Pond and Well

In 1983 and 1984, the John Bartram Association developed a master plan for the landscape, which sparked an interest in the property’s historic pond. The pond, known from early drawings of Bartram’s Garden, was no longer visible. The goal of these investigations was to uncover its original location and restore it. Using resistivity testing, archaeologists located what they believed was the saturated clay base of the pond. Years later, in 1996, archaeologists revisited this area and found layers of sediment and artifacts, including traces of the 18th-century pond bank. The following year, more digging exposed the outline of the rest of the pond. Since the natural sediment beneath it would not have kept the water from draining out, the pond must have been partially manmade and shored up using watertight materials. Archaeologists and historians also believe there was once an underground connection between the pond and the spring house on the property, but they have not yet been able to locate it.

In 1982, the brick pavement around the house collapsed, revealing a historic well. The well was likely constructed in the mid-18th century as indicated by associated artifacts including bricks. It was demolished during renovations to the property in the 1950s. While only a few artifacts have been recovered from the base of the well, deeper excavations may reveal more material dating to the early Bartram family. These excavations show that even a garden containing natural-looking features and a wilderness-type design required extensive effort and upkeep to maintain its appearance.

A blueprint for the Seed House and dig sites.
2008 Seed House Archaeological Plan, showing the four rooms of the complex. Image courtesy of Joel Fry, Bartram’s Garden.

Changing Technologies

The Bartram family is also remembered for advancing the technologies used to grow both local and exotic plants on their property, beginning with a single early greenhouse in the 1760s and expanding to several hothouse and greenhouse buildings in the early to mid-1800s.

1760 Greenhouse

John Bartram constructed his first greenhouse around 1760. At the time, it was one of only six in the Philadelphia area. It was one room in a complex of rooms that became known as the “Seed House.” Dr. Schuyler and Matthew Parrington led an investigation of this structure in conjunction with a 1979 Historic Landmarks Survey. Despite the fact that the building is called the Seed House, there is no archaeological or historical evidence indicating that the Bartrams used it to store seeds. Each of the four rooms in the complex, which were added independently, served a different purpose to facilitate the garden business.

The greenhouse (Room 1) is not the oldest room in the seedhouse complex. Room 2 is likely slightly older and was constructed as a small storage shed around 1759. Both rooms contain archaeological information about the functioning of John Bartram’s early greenhouse. Room 2 contained large quantities of flat glass, and archaeologists have dated this glass to the 18th century. Wistarburg Glass Works, a famous glassmaking facility founded in Salem County, New Jersey, in 1739, could well have provided the glass for John Bartram’s original greenhouse. Unlike later greenhouses made entirely of glass, this early greenhouse would have had three stone walls and a full roof, and only one south-facing wall would have contained panes of glass. It is possible that John Bartram stored the glass for his greenhouse (Room 1) in his storage room (Room 2).

This original greenhouse eventually fell out of use and is not listed in an 1837 inventory of glass greenhouses at Bartram’s Garden. However, clues in the stone foundation of Room 1 helped archaeologists correctly identify it as the former greenhouse. In the foundation of the room is a rectangular opening where a “Pennsylvania Fireplace” was once installed to provide heat during the cold winter months, and additional openings suggest a careful arrangement of flues to move the hot air around the base of the room, beneath what would have been a raised platform that held the greenhouse plants.

Black and white photo of the interior of the greenhouse at Bartram, a small amount of debris on the ground but otherwise empty.
The interior of John Bartram’s 1760 greenhouse still retains many original features. On the right, a large square hole indicates where the Pennsylvania Fireplace once stood. To the left, two small holes in the wall likely served as flue ventilation from the fireplace. The flues would have circulated warm air underneath the wooden planks upon which plants were placed. The plants also had access to the single wall of glass in the greenhouse, now covered over with wooden boards. Image modified from HALS PA-1-B-16. Public domain.

Later Greenhouses

As the Bartrams’ business expanded and horticultural technologies developed, their greenhouse needs also expanded. In 1980, archaeologists were digging test pits on the property near the Coach House, when they found at least two additional structures. This area is full of traces of activity from the first half of the 19th century, when Ann Bartram Carr and her husband ran a large- scale commercial nursery. Archaeologists believe that they uncovered the “Greenhouse and Orange House,” which were built by William Bartram and John Bartram Jr. in 1800.

They also discovered remnants of a building known as the “New Holland and Stonehouse,” which was built by Robert Carr in 1817. This heated greenhouse contained many artifacts including hundreds of ceramic flowerpot fragments (for an analysis of flowerpots from The Woodlands, see Boileau’s article in this issue), a reminder that the Bartrams also grew their plants and seedlings within these vessels. This building also yielded an exciting find that harkened back to the first greenhouse on the property. As part of its flooring, a unique cast iron plate was laid out horizontally. It contained a depiction of a large sun and was discovered to be the front piece of a Pennsylvania Fireplace. This artifact, from a metal-lined stove also called a Franklin Stove, can be dated to ca. 1760 due to the decorative floral motifs, indicating it was likely the one used by John Bartram in his original greenhouse. While it is unclear why it was moved to this building, it is apparent that John Bartram’s legacy continued to live on in the later greenhouses.

Blueprint for the nursery and barnyard dig sites.
2008 plans of the nursery and barnyard archaeological excavations, indicating locations of units near the Coach House. Image courtesy of Joel Fry, Bartram’s Garden.
Front plate of the Bartram fireplace, showing a sun with a face.
Front plate of the Pennsylvania Fireplace that was in John Bartram’s original 1760 greenhouse. Photo courtesy of Joel Fry and the John Bartram Association.

The Roots of the Past

Archaeological investigations have added to the scholarship and information about Bartram’s Garden, and they allow for a better understanding of how the gardens have changed through time. This helps historians draw connections between changes in the Bartram family business and the larger picture of early American history, particularly changing horticultural technologies and the growing trans-Atlantic botanical trade. Visitors to the Garden today enjoy historically accurate depictions of the estate, thanks to the work of professional gardeners, scholars, students, and volunteers. When the buildings or grounds are in need of restoration that could potentially damage artifacts and disturb the garden soils, archaeologists recover and preserve this crucial information before any further work is carried out.

The Pennsylvania Fireplace

The Pennsylvania Fireplace is a style of metal-lined stove intended to produce more heat, less smoke, and better air circulation than a traditional 16th-century open fireplace. They are sometimes called Franklin Stoves, as Benjamin Franklin published a design for one in 1744. This original design was improved upon throughout time, particularly as scientific understanding of thermodynamics developed.

Diagram of the pieces for a Pennsylvania Fireplace.
Benjamin Franklin’s original design for the Pennsylvania Fireplace, from his 1744 “An Account of the New Invented Pennsylvania Fireplaces.” Public domain.

John Bartram and Benjamin Franklin were two of the founders of the Philosophical Society, now the American Philosophical Society, in Philadelphia in 1743. Franklin was familiar with Bartram’s botanical interests and his natural history work. It makes sense that Bartram would have known about Pennsylvania Fireplaces and might have been gifted one by Franklin to heat his greenhouse. The motifs on the Pennsylvania Fireplace found at Bartram’s Garden indicate that the front plate was produced between 1760 and 1766, when the first greenhouse was in use.


I am thankful to the scholars whose work I detail here. My communications with Joel T. Fry and Dr. Robert Schuyler, in particular, were crucial to the writing of this piece.

Alexandria Mitchem is a Penn alumna (C16) and current Ph.D. candidate in the Department of Anthropology at Columbia University. She is an archaeologist studying botanical science, business, and politics in the Early Republic period.


Fry, J.T. “Archaeological Research at Historic Bartram’s Garden.” Bartram’s Broadside, Summer 1998.

Jacobs, J.A. “Historic American Landscape Survey: John Bartram House and Garden, Greenhouse (Seed House).” Historic American Landscape Survey no. PA 1-B History Report. National Parks Service: United States Department of the Interior, Summer 2001.

Cite This Article

Mitchem, Alexandria. "Unearthing the Roots of the Past." Expedition Magazine 62, no. 3 (September, 2020): -. Accessed April 19, 2024. https://www.penn.museum/sites/expedition/unearthing-the-roots-of-the-past/

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