The Evolution of Tree Care Continues at Longwood Gardens 

a forest with green trees and the shining sun

Kennett Square, PA–Trees are firmly rooted in the history of Longwood Gardens, anchoring past to present and connecting nature with people across generations. Many of the trees on Longwood’s property date back more than 200 years, including some notable specimens brought to the property in the late 1700s by early plant explorers Joshua and Samuel Peirce. In 1906, Pierre S. du Pont purchased the property to save the old growth native forests and the collection of historic trees the Pierce family had carefully curated from being turned into lumber. Fast forward to today and the care and conservation of trees continues to remain a priority at the display garden. 
Longwood’s Level IV Accreditation, the highest level awarded by The ArbNet Arboretum Accreditation Program and The Morton Arboretum, has been renewed, affirming the importance Longwood Gardens places on supporting tree conservation. The ArbNet Arboretum Accreditation Program is the only global initiative to officially recognize arboreta at various levels of development, capacity, and professionalism. Level IV accreditation requires employment of well-qualified tree scientists engaged in publishing sophisticated research, management of living tree collections for the purpose of conservation, and that the arboretum takes an active role in supporting tree conservation. There are 39 arboreta worldwide that have achieved this recognition. Longwood first received Level IV accreditation in 2015.

“Conservation is at the forefront of our minds when caring for our trees,” says Kate Santos, Director of Science. “We’ve initiated a multi-pronged approach to safeguard these magnificent trees and our tactics evolve as the needs of the trees do. Our current research is focused on identifying the best strategies to manage invasive species, increase biodiversity, and strengthen the climate resiliency in our historic woodlands.” 

Caring for the more than 1,100 types of trees that call Longwood home depends on efforts from staff across departments. Detailed management plans ensure the long-term perpetuity of tree collections, while regular assessments and maintenance by arborists keep trees in top shape. Research conducted by Longwood helps bridge the gaps needed to protect species that are threatened, and the Land Stewardship and Ecology team focuses on monitoring and improving the quality of old and new growth forests that spread across 750 acres of natural lands.

In 2008, Longwood developed a tree management plan to guide the care of historical trees and then added climate change modeling to the plan in 2013 to help make informed decisions when selecting trees for new plantings or replacements. Through the Specimen Tree Replacement Plan, Longwood preserves the germplasm, or genetics, of certain trees — original trees dating back to the 1800s, state champion trees, and those valuable to the aesthetic landscape of the Gardens. By propagating and cloning those trees, Longwood creates genetically identical specimens that ensure the best traits endure for centuries to come. Examples of these trees are Longwood’s historic yellow cucumber magnolia (Magnolia acuminata var. subcordata ‘Peirce’s Park’) and Gingko biloba.

Recently, the Arborists team began assessing the health of the trees across Longwood Gardens using sonic tomography which provides them with two-and three-dimensional images to determine whether there are any cavities in the tree.

“Our trees are vital to our ecosystem, our history, and our plant research,” Santos added. “We go to great lengths to ensure our trees remain central to the beauty of Longwood for generations to come.”

Plus, Longwood has the most reported champion trees in the state of Pennsylvania—a towering 63 Pennsylvania champion trees, those specimens of a particular species or variety that are the largest recorded. 

Robust education offerings complement Longwood’s tree care practices and encourage guests to think about these green giants beyond their visit. Visit to learn about upcoming in-person and online classes on woody plants. 

About Longwood Gardens
In 1906, industrialist Pierre S. du Pont (1870-1954) purchased a small farm near Kennett Square, PA, to save a collection of historic trees from being sold for lumber. Today, Longwood Gardens is one of the world’s great horticultural displays, encompassing 1,100 acres of dazzling gardens, woodlands, meadows, fountains, a 10,010-pipe Aeolian organ, and grand conservatory. Longwood Gardens is the living legacy of Pierre S. du Pont, bringing joy and inspiration to everyone through the beauty of nature, conservation, and learning. Open daily, Longwood is one of more than 30 gardens in the Philadelphia region known as America’s Garden Capital. For more information, visit       

About ArbNet 
ArbNet is an interactive, collaborative, international community of arboreta. ArbNet facilitates the sharing of knowledge, experience, and other resources to help arboreta meet their institutional goals and works to raise professional standards through the ArbNet Arboretum Accreditation Program. The accreditation program, sponsored and coordinated by The Morton Arboretum in Lisle, Illinois in cooperation with American Public Gardens Association and Botanic Gardens Conservation International, is the only global initiative to officially recognize arboreta based on a set of professional standards. The program offers four levels of accreditation, recognizing arboreta of various degrees of development, capacity and professionalism. Standards include planning, governance, public access, programming and tree science, planting and conservation. More information is available at