Longwood Gardens is acquiring a 500-acre estate from the du Pont family

Longwood Gardens, the nearly 1,100-acre botanical garden in southern Chester County, has agreed to acquire the Granogue estate, 505 acres of rolling woods and farmland and a hilltop stone mansion, along the Brandywine in nearby northern Delaware.

Granogue was the home of Irénée “Brip” du Pont Jr., an engineering executive and heir to the munitions and chemical company fortune, who died Jan. 16 at age 103.

“There are no real plans yet, other than to preserve the 505 acres, and to make it available for the public to enjoy,” said Ben du Pont, a cousin of Irénée’s. Terms of the acquisition and a timetable for opening to visitors have not been disclosed.

Two foundations controlled by branches of the du Pont family — the Longwood Foundation, which funds Longwood Gardens, and the Mt. Cuba Center, which manages an estate and programs focused on native plants, near Hockessin, Del. — “each made generous contributions to fund the land acquisition,” said Caroline Ralston, a spokeswoman for Mt. Cuba, in an interview Thursday.

The Conservation Fund, a national group that advises wealthy donors on land preservation and financing, helped bring the deal together, following talks that began in 2016 and focused on the du Pont family’s desire to conserve the properties for future public use — both events and passive recreation, said Paul Redman, chief executive at Longwood Gardens, in an interview Thursday.

Longwood says 1.6 million people visited the gardens along Route 1 in the year ending Sept. 30, making it one of the state’s top tourist destinations.

The steeply rolling land at Granogue, including extensive oak and beech trees, stone water towers and ponds, paved and unpaved roads and at least two farm properties grazed by cattle and planted with corn and soybeans in recent years, lies west across the Brandywine River from a 1,300-acre wooded expanse of First State National Historical Park. The property is north of Delaware’s Brandywine Creek State Park.

The neighborhood and nearby locales along the curved Delaware-Pennsylvania state line are known locally as the “chateau country” due to the prominence of several former estates built with profits from the family-founded DuPont Co. munitions and chemical empire. The Hagley industrial museum, Bellevue State Park, Nemours Children’s Hospital and the Nemours Estate, Mt. Cuba Center, Winterthur Museum, Garden & Library, Brantwyn Estate, and Longwood Gardens itself are all former du Pont family properties.

The castle-like stone Granogue house, which contains an original Maxfield Parrish mural, was built by Irénée du Pont Sr., whose father and uncles reorganized the family gunpowder business into the vast DuPont Co. chemical works in the early 1900s. DuPont Co. became the most valuable company in the world by the 1950s.

The family’s holdings were diluted by the 1970s, though members remained represented on its board for some time after. DuPont Co. has since added and split off many business units, and lacks its former dominating size.

The younger Irénée was an MIT-trained engineer who worked as a DuPont Co. executive, took a leading role in setting up and expanding Wilmington University, and introduced himself to Iowans as “Ernie” during the 1988 campaign for the GOP presidential nomination by his cousin, Delaware Gov. Pierre S. du Pont.

On his long watch, Granogue hosted Boy Scout camporees and charitable and political fund-raisers, among other events.

U.S. Sen. Chris Coons (D., Del.) has recounted that du Pont told visitors he had not chosen to be born the owner of the estate, but considered that it was a public trust he hoped to save from development.

Family members will continue to live in homes on the property in the near future.

The family is descended from Eluthere Irénée du Pont de Nemours, who built a pioneering gunpowder mill on the Brandywine at the suggestion of his friend Thomas Jefferson.