Haverford College Arboretum is hosting a free lecture Sunday, Sept. 13, on how to choose tree species that can survive warming temperatures and new pests threatening Main Line landscapes.

George Coombs, director of horticulture at Mt. Cuba Center in Delaware, will present "Trees for a Changing Climate" in Sharpless Hall at the arboretum, 370 Lancaster Ave. in Haverford, according to the arboretum's event listing. A free campus tour led by arboretum horticulturists begins at 2 p.m.

The talk is part of an annual lecture series co-sponsored by the arboretum, the Hardy Plant Society and the Henry Botanic Garden, a 46-acre wilderness garden in Gladwyne.

Coombs leads Mt. Cuba Center's Resilient Tree Canopy Project, which uses U.S. Forest Service data and climate-modeling tools to rate which native species will thrive as the region warms. The project assigns each species a confidence tier, ranking trees from "no concern" to "avoid."

In a November 2024 interview with A Way to Garden, Coombs described the stakes: "There are so many threats for our native trees … emerald ash borer, beech-leaf disease, there's all kinds of what I would call species catastrophic diseases that really are going to change the way that our landscape looks …"

In that same interview, Coombs said climate projections show Philadelphia's future weather could resemble southern Maryland under moderate warming or Memphis, Tennessee, under a high-warming scenario. He stressed that trees planted now will still be standing at the end of the century under a very different climate, making species selection critical for homeowners and land managers.

Early results from the project suggest red maple, sweetgum, tulip poplar, white oak and sycamores should remain strong performers in the region, according to Mt. Cuba's analysis.

The arboretum's event description said adapting planting practices is essential to protect and sustain local landscapes against climate change and novel pests. Coombs will walk attendees through Mt. Cuba's recommended species list and the methods the center plans to use to track tree resilience over the coming decades.

The lecture is free, but registration is required through Eventbrite. Light refreshments will be served.

Coming up

  • Saturday, Sept. 19: Wayne PorchFest brings 48 acts to car-free streets in downtown Wayne.