Growing and Caring for the Franklinia
Cultivating Botanic History in Your Garden
Learn more about growing and caring for the Franklinia alatamaha tree, also known as the Franklin Tree or simply Franklinia, and the legacy of this striking and unusual plant.
Franklinia blooming in the Common Flower Garden by the Historic Bartram House.
Cultivation Requirements
The success of growing a Franklinia depends on proper site selection and careful pre-planting preparations. Ideal cultural requirements include:
- Good drainage conditions
- Acidic soil
- Protection from strong winds
- Mulch over the root area
- Light shade
See below for more details about how to assess and achieve each of these requirements.
Good Drainage
Successful Franklinia trees are generally found growing on hillside sites or in sandy soil, both of which are conditions that provide excellent drainage. The Franklinia does not fare well in a damp or swampy site, as it tends to develop root rot.
In selecting a planting site, dig a test hole to evaluate the soil’s porosity. To test drainage, pour water into the hole until it is half-full. Allow the water to soak into the ground, then refill. The second time, measure the rate of fall in the water level: in order to be appropriate for planting Franklinia, the water should drain at a rate of more than one inch per hour.
Once adequate drainage has been demonstrated, the planting hole can be fully dug and filled with the planting mixture.
Acidic Soil
Much like azaleas, Franklinias prefer acid soil conditions, and under cultivation do well in humus-rich or peaty soil. A pH between 5–6 is optimal. Deep woods dirt typically has an adequate acidity level.
While an acid soil is preferable, Franklinias frequently tolerate less than ideal conditions.
If you do not know the acidity of your soil, soil testing is available through Penn State Extension locations or by mail; testing kits are also sometimes available at commercial garden centers.
Wind Protection
The Franklinia does not do well in a windswept site. A wooded hillside facing away from prevailing winds is ideal. The tree can be interplanted with other Ericaceous plants.
However, do not plant the Franklinia too close to a building, as the walls reflect light and heat, creating artificial conditions.
Mulch
Like most forest plants, the Franklinia appreciates mulch over the root area to ensure a proper level of moisture for the roots during dry periods and to prevent rapid changes of temperature in the root zone.
Composted pine needles, shredded oak leaves, two-year-old decayed wood chips, or other acid organic materials are appropriate mulches for Franklinia.
Light Shade
The Franklinia tolerates varying amounts of sunlight and will grow in dense shade as well as full sun.
Although full sun provides the most blossoms and more brilliant fall colors, there are indications that light to moderate shade (about a half-day of sunlight) has cultural advantages, as Franklinias growing in full sun can show signs of stress in long periods of intense heat.
The Franklinia grows more slowly and blooms sparsely in dense shade.
Fall Franklinia foliage: a tongue-twister and a beautiful addition to the landscape.
Planting the Franklinia
With proper care, a Franklinia can be planted directly in its permanent site.
It can be planted any time in the fall after it loses its leaves or in the early spring after the threat of frost is over. For spring planting, Franklinia should be planted no later than mid-May.
It normally does not do well as a container plant.
Preparing the Planting Site
The Franklinia needs a deep, well-prepared planting hole at least twice the size and depth of the containered plant.
Prepare the hole and fill it with an appropriate soil mix:
- If the soil is clay, rocky, or almost pure sand, replace it with a planting mixture of 1/3 sand, 1/3 existing soil (for sandy areas substitute clay soil for moisture retention), and 1/3 organic matter such as two-year-old decayed wood chips and composted leaves or bagged composted pine bark.
- If using peat moss, be aware that it has a tendency to dry out very quickly, which could endanger the Franklinia during dry spells.
- If adding sand, use a type that is granular, like traction grit, not builder’s or sandbox sand.
Care at Planting Time
Scoop out a hole in the planting mix as large as the root ball. Carefully remove the Franklinia from its container and set it in the hole, leveling the top of the root ball with the level of the ground at the sides.
Water the plant thoroughly and then replace the planting mix, firming lightly. Add the mulch.
Do not fertilize at planting time.
Water on a regular basis after planting, but do not over-water.
The Franklinia’s natural tendency is to develop multiple trunks, as seen here.
Caring for the Franklinia
The Franklinia can be both challenging and rewarding to grow.
Pruning
The Franklinia has a natural tendency to develop multiple trunks. If a single-trunk tree is desired, prune secondary trunks as they develop.
Otherwise, little pruning is required. Do not prune any die back until new growth commences in the spring.
Acidity & Fertilization
Test the soil’s acidity periodically and correct as needed. If a test shows a pH above 6, consider either a liquid or granular fertilizer for such Ericaceous plants as azaleas. Fertilize carefully, only in April or November but never in late spring or summer.
Be aware that lime, often used on lawns and in potting soil mixes, works against acidity, drastically altering the soil pH and endangering the Franklinia.
Mulching
Composted pine needles, shredded leaves, and two-year-old decayed wood chips make satisfactory mulches.
Maintain the mulch at about three inches deep as needed. It should begin a few inches from the trunk, to prevent bark damage in the winter from rodents. and extend out past the drip line of the tree. Keep the mulched area free of weeds and grass, but do not cultivate the surface roots of the Franklinia.
Do not use limestone or marble chips as mulch.
Watering
Ensure that the Franklinia is adequately watered–at least weekly–through the fall when it is still growing and flowering. The Franklinia wilts easily and has difficulty recovering if allowed to dry out.
Provided there is good drainage, thorough watering during periods of drought is essential. Note that planting holes with a high percentage of peat moss tend to dry out quickly if not watered frequently.
Growing Franklinia from Seed
Plan for spring germination by sowing seeds into a flat at the beginning of winter.
Franklinia seed will germinate upon being shifted to 70 degrees after 90–140 days of moist cold stratification at 40 degrees.
Upon germination, keep the seedlings in an acidic soil mix, such as peat and pine bark, in shallow pots and prevent from drying out.
William Bartram’s illustration of the Franklinia.
About the Franklinia
Franklinia alatamaha is the signature tree of Bartram’s Garden, but it is not native to Philadelphia: John and William Bartram had their first encounter with Franklinia in 1765 in a small grove along the Altamaha River in what is now known as southern Georgia, on the land of the Muscogee Nation. In 1777, William Bartram transported seeds back to Philadelphia for cultivation and named the plant Franklinia in honor of his father’s close friend Benjamin Franklin.
The plant has not been found in the wild since the early 19th century, but continued cultivation by the Bartrams and by many other nurseries has kept the Franklinia in the landscape. All current Franklinia are descended from those originally grown by the Bartrams, including numerous specimens within Bartram’s Garden and those for sale in our nursery.
The Franklinia is notable for its large, fragrant white flowers in late summer. The plant’s deciduous leaves often begin turning vibrant shades of red and orange even while the Franklinia is blooming, making for a striking contrast. The Franklinia is a member of the tea, or camellia, family and is closely related to the Stewartia and Gordonia.
Learn more about the history of the Franklinia.
Frequently Asked Questions
Where can I buy a Franklinia?
We are proud to sell Franklinia through our nursery, which makes plants available when outdoor planting is appropriate: in this case, typically spring and fall. Plants cannot be shipped and must be picked up from Bartram’s Garden. Click here to see current plant inventory and make your purchase online. Plants cannot be reserved in advance or held for long periods of time.
Franklinia are also available through many independent and commercial nurseries. Because the plant is extinct in the wild, all Franklinia in the world are descended from those originally cultivated at Bartram’s Garden.
Eek! Can you help with my Franklinia?
Though our horticulture staff are very skilled at caring for the Franklinia at the Garden along with the rest of our 50-acre landscape, they unfortunately cannot visit or care for your tree, and they are typically not available to consult on Franklinia issues.
We recommend working with a licensed arborist and using this guide as well as other professional resources to support care for your Franklinia.
Can I register my Franklinia with Bartram's Garden?
A Franklinia census was conducted in 2000 as part of a campaign to increase awareness about these lovely trees, but we do not maintain an ongoing list of all Franklinia.
Is this an easy plant to grow?
Not usually! The Franklinia is not for the faint-hearted: we often say that it takes both courage and luck to grow successfully. But we think it’s worth it!
These recommendations were gathered from a number of expert sources, including guidance from the former American Franklinia Society, William Cullina, Kathleen Salisbury, and many gardeners and growers, both professional and amateur, who have shared their insights and experiences with growing Franklinia.
You may also be interested in:
Bring the Garden home!
Shop for plants and seeds in our nursery.
Botanic Garden & Natural Lands
America’s oldest surviving botanic garden is still growing.
Honoring Shared Histories
Learn more about the known history and current research of this storied landscape.
