Unlike other du Pont family gardens in Delaware and Pennsylvania, the Mt. Cuba Center’s mansion is used for office space rather than part of site tours. Here, the focus is on Delaware’s flora.//photo by Joe del Tufo
It’s summer solstice, and there’s a steady arrival of cars turning off Barley Mill Road into Mt. Cuba Center, a former du Pont family estate located on a remote hilltop a few miles east of Hockessin. The driveway ascends steadily and winds along the side of the hill, overlooking the picturesque valley below.
Outside the old mansion, now converted into office space, lines are forming around food trucks. The front doors are open, guiding visitors through the house and onto the back terrace, where wine and beer vendors are warming up the crowd. People are milling around the gardens. Across the expansive back lawn, on grass as thick and soft as egg crate memory foam, adults recline on picnic blankets and folding chairs while their children roam in packs, investigating plants, bugs and various other things, the way children do.
This event, Twilight on the Terrace, is designed to get people through the doors, for unlike other du Pont legacy institutions—Winterthur, Nemours, Longwood—Mt. Cuba Center is not exactly a household name. The institution is young: established as a nonprofit private foundation in 2002, general admission did not begin until 2013 and was only expanded to five days a week in 2016. Of the events held annually at Mt. Cuba Center, none attract crowds and fanfare comparable to Point-to-Point at Winterthur or Christmas at Longwood.
Mt. Cuba Center has used its immense financial resources to fund more
Family events like this allow Mt. Cuba Center to raise its profile while connecting visitors to the most visible legacy of Pamela Cunnigham Copeland (1906-2001) and Lammot du Pont Copeland (1905-1983): the 1935 red brick Colonial Revival style mansion, the stunning formal gardens designed by Marian Coffin in 1949, and the naturalistic gardens—17 acres of forests, creeks, ponds, and meadow—exactly the kinds of attractions audiences have come to expect when visiting old du Pont estates.
But for as much as the house and gardens catch the eye, behind the scenes, Mt. Cuba Center has quietly grown into an experimental station for ecological sustainability. In greenhouses and trial gardens, and across more than 900 acres of natural lands, teams of horticulturalists, arborists, ground managers and volunteer citizen scientists are carrying out conservation projects on a massive scale.
“The Copelands’ ambition for their garden wasn’t just to be a public garden but to be this tool to inspire conservation,” says Jeff Downing, executive director at Mt. Cuba Center. Downing is quick to point out that the gardens are crucial to inspiring visitors to include more native plants around homes and businesses. Mt. Cuba Center has even started offering classes, which have so far enrolled more than 900 students, to develop what Downing calls “a community of conservationists.”
Mt. Cuba Center has also used its immense financial resources—approximately $320 million in assets—to provide financial backing for more than a dozen conservation projects that have preserved in excess of 15,000 acres, including 1,100 acres to create First State National Historic Park. As this magazine reported in 2016: “If you’re driving through the state of Delaware, you’re going to pass something that the Mt. Cuba Center has helped protect.”
But when it comes to research, Mt. Cuba Center is hoping to make an impact in more subtle ways, like using its gardens to document the ecological benefits and disease resistance of native plants and then sharing those results with plant nurseries and retailers. Or working with the state botanist to breed rare and endangered plants. Or conducting decades-long reforestation experiments. The list goes on.
“We want to create a broader landscape with more native plants that perform a wide variety of ecological services like reducing flooding and capturing carbon and keeping fresh drinking water for people and providing habitat for all sorts of other organisms,” says Travis Beck, director of horticulture at Mt. Cuba Center. “Ultimately, the goal of Mt. Cuba is to change the world.”
Of the 1,083 acres of land managed by Mt. Cuba Center, the main complex and adjacent gardens comprise 64 acres, and 95 acres are leased to the Delaware Nature Society for the Ashland Nature Center. The remaining 924 acres are known as the “natural lands.” It is here that some exciting research is beginning to take shape.
To get there, Travis Beck climbs behind the wheel of a hulking Chevy Silverado 2500. After circling the property, Beck turns off the main road and onto a pathway mowed through the pasture. The grass reaches over the hood.
“These are really just hay fields, but we leave them up until this point in the year because we have populations of ground-nesting birds,” says Beck.
The scope of conservation efforts happening at Mt. Cuba is staggering. Every 100 yards or so, Beck points to something else that’s measured, to some other experiment that’s underway. They monitor the water quality of Hickory Run, a tributary of Red Clay Creek, documenting everything from dissolved oxygen to insects and other wildlife. Digital tools provide up-to-date readings on things like carbon sequestration and pollution reduction. Researchers are doing a survey of Mt. Cuba’s bee population; meanwhile, grounds managers plant between 1,000 and 3,000 plants annually, mostly natives, to provide the bee population with a year-round food supply. There are 83 vegetation survey plots where tree populations are recorded every five years along with reptile and amphibian surveys.
Turtles are among the wildlife that thrive in the Mt. Cuba Center’s Natural Lands, set aside to study how nature manages itself when left alone by humans. Below, wild seeds native to Delaware are propogated for study and eventual planting around the gardens.//photo by Joe del Tufo
He points to an orchard. “They’re experimenting with hybrid backcrossed American Chestnuts that might be resistant to the chestnut blight. Researchers will inoculate them with the fungus, and most of them will die, but perhaps some of them will survive, and then those will become genes for the next generation of crosses.”
And then there’s the reforestation experiment, a three-and-a-half-acre site containing 2,700 trees and shrubs surrounded by an eight-foot wire fence supported by utility posts. In the coming years, more than 100 acres of natural lands need to be reforested, Beck says, and he was disappointed to find few reliable, large-scale academic studies relevant to what they wanted to achieve.
So Mt. Cuba Center set about doing the research itself. The experiment, set to run through 2035, is currently in its third year; Beck predicts at least 10 years before they can draw any conclusions. It isn’t much to look at now, mostly just small, evenly-spaced rows of trees growing in a pasture. However, toward the center of the enclosure, a thicket of trees is growing tall and dense, so much that it’s killing the grass. Beck only gets a few feet into the thicket before turning back. He looks pleased.
“Over here, it’s proven to be quite aggressive,” he says, hesitant to claim anything definitively before explaining that in this area, canopy trees were planted just five feet apart, intermixed with groundcover and shrubs, as opposed to 10 feet apart. “Interestingly, the trees seem to sense when they’re in competition with their neighbors, and so they put on more biomass and grow up faster.”
On the way back to the truck, I ask Beck what all this means. Is the reforestation project representative of something bigger?
“I think there really is a role for people in managing our landscape,” he responds. “We can’t entirely trust nature to heal itself.”
Two weeks after Twilight on the Terrace, Jeff Downing and Sara Stevenson, director of audience development, are walking through Mt. Cuba Center’s 15,000-square-foot Trial Garden. Despite the afternoon heat, Downing speaks and gesticulates with the enthusiasm of a guy who clearly loves his job.
The idea of the Trial Garden is simple: test as many varieties of as many different native plants as possible. Trials typically last for three years. Some of the plants come from local nurseries; others are exceedingly rare, found only in the wild. After the first year, the plants are left to fend for themselves, no water and no pesticides. Then, Mt. Cuba Center’s team of volunteer citizen scientists monitors each plot weekly and documents disease resistance, hardiness, bloom time, floral display and attractiveness to pollinators. Some die, but most survive. All of this data is collected, analyzed, and published in formal research reports.
Sara Stevenson, director of audience development at Mt. Cuba Center in Hockessin.//photo by Joe del Tufo
“It’s kind of like Consumer Reports for plants,” says Downing. “These trials are designed to hit two audiences: potential consumers to say, look at these beautiful plants that you could put in your yard, but also for the nursery industry, because the nurseries use that performance data because they want to grow things that are going to be successful so that they have happy customers.”
Ultimately, Downing suggests, the impact of their research will be measured through a survey of the catalogs of the largest wholesale plant nurseries in the Mid-Atlantic region. About two years ago, Mt. Cuba Center conducted the first such survey and found that only 24 percent of available plants were native. The hope is that future surveys will begin to show more widespread availability of native plants for the average consumer, which will benefit the entire ecosystem.
“In our urban and suburban environments, we’re starved of a lot of plants, especially native plants that birds rely on because they feed on the insects that feed on the plant,” says Downing. When our ecosystems lack native plants, he suggests, we essentially transform our homes and neighborhoods into food deserts. “So in trying to keep a healthy ecosystem every step of the way, if you don’t have the right plants, you are missing a rung in the food chain.”
“Once you know a little bit more about the plants and the kind of ecological impact they can have, you’ll see the results of it,” says Stevenson. “You’ll see butterflies. You’ll see caterpillars. We want people to realize that it doesn’t take much: in a container garden, a couple of plants, it makes a big difference.”
Because so many of the plants in the Trial Garden are not available commercially, Mt. Cuba Center coordinates with Delaware state botanist Bill McAvoy to identify rare varieties that grow only in the wild. Using those seeds, the plants are then propagated in greenhouses.
“We’re trying to figure out, how do you grow these things because some of these plants, you look them up, and nobody knows how to grow them because they only grow in the wild,” says Eileen Boyle, director of conservation and research.
Rare varieties of plants are propagated in Mt. Cuba Center’s greenhouses.//photo by Joe del Tufo
In a building adjacent to the greenhouses, she and her team are up to their elbows in potting soil. There must be hundreds of plants in here, on shelves and stainless steel tables, each tagged with an identifier, and hundreds more in the greenhouses, some of which are just beginning to germinate in compostable tubes. In an industrial walk-in cooler, seed containers line the shelves.
“Depending on what it is,” says Boyle, “you have to put it in the refrigerator for 30, 60 or 90 days to make-believe that it’s winter so the seed knows when to grow.” When it’s time to remove seeds from the cooler, the seeds “think” it’s spring. “The seeds need to wake up.”
When asked how many plants are grown here every year, Boyle takes a moment to ponder the question. “Thousands.”
Everything at Mt. Cuba Center—formal gardens, naturalistic gardens, trial gardens, natural lands, greenhouses—exists to improve the ecological sustainability of Delaware and the world. It’s a grandiose mission, one that motivates the team at Mt. Cuba Center to do what they do.
“We’re on a mission,” says Beck, “one that is all about native plants, conservation, and improving the environment.”
Ultimately, this mission is what distinguishes Mt. Cuba Center from other du Pont family legacy institutions like Longwood Gardens or Winterthur. And unlike those institutions, the staff at Mt. Cuba Center have wildly different metrics for measuring success.
“I’m not really going to be satisfied until we have bear coming through here regularly,” says Beck. “That would really be the sign that we’re succeeding not just on our property but also connecting to a larger network of natural landscapes that an omnivore with a larger range can utilize so that we’re not just a disconnected little piece of perfect nature.”