River Farm (25 acres/10.1 ha), currently home to the American Horticultural Society (AHS) headquarters, is a 27-acre landscape located at 7931 East Boulevard Drive, Alexandria, Virginia. The estate takes its name from a larger plot of land which formed an outlying part of George Washington's Mount Vernon estate.
The River Farm property was established in 1653–54 by Giles Brent and his wife, Mary Kittamaquund, a princess of the Piscataway tribe. Brent received a grant of 1,800 acres (7.3 km2) named Piscataway Neck. In 1739 his successor George Brent transferred the property to his brother-in-law William Clifton, who renamed the property Clifton's Neck. In 1757 Clifton completed the brick house that now serves as AHS headquarters.
Following financial difficulties, Clifton sold the land to neighbor, founding father George Washington, who obtained the property for £1,210 through a bankruptcy sale in 1760. Washington changed the name of Clifton's Neck to River Farm and leased the property to tenant farmers.
River Farm was passed down through two immediate generations of Washingtons and later sold with 652 acres of Washington's original land to the Snowden brothers of New Jersey. This included the houses known as "Wellington," "Waynewood," and "Collingwood." The property was home to numerous owners including Malcolm Matheson, who bought the property in 1919. Matheson placed the property on the market in 1971 and received an offer from the Soviet Embassy who planned to use the land as a retreat or dacha for its staff.
After Matheson took his land off the market to avoid the Soviet sale and vocal public opposition, Enid Annenberg Haupt, philanthropist, gardener, and member of the AHS Board of Directors took interest in the property. AHS purchased the property in the 1970s and Haupt donated funds over several years to help AHS pay off the mortgage. While under the ownership of AHS, she expressed a desire to see the grounds kept open to the public. In 1973, AHS relocated its headquarters from the city of Alexandria to nearby River Farm. The property was renamed River Farm in honor of President George Washington, one of the many land owners.
Today's smaller River Farm is located on the northernmost division of Washington's original property. River Farm features a 1920s estate house with naturalistic and formal garden areas. It still preserves several historical associations with Washington. Its Kentucky coffeetrees are descendants of those first introduced to Virginia upon Washington's return from surveys in the Ohio River Valley. The estate's oldest tree is a large Osage-orange (Maclura pomifera), believed to be the largest in the United States. An old, incorrect, tale claimed it was a gift from Thomas Jefferson to the Washington family, and grown from seedlings of the Lewis and Clark Expedition of 1804–06.
In 2004, River Farm was designated a Horticultural Landmark by the American Society for Horticultural Science. This recognition was due to the ability to retain its historic character while at the same time showcasing the best and most environmentally responsible gardening practices. Horticultural Landmark features include vistas stretching down to the Potomac River as well as its artful blend of naturalistic and formal gardens that offer year-round delight to visitors of all ages. In addition, there are extensive and creative play areas for children, demonstration gardens for both edible and ornamental plants, a four-acre meadow, and scenic resting places for picnickers, artists, and romantics. Other highlights include two small buildings with planted "living" roofs, one of the largest Osage-orange trees in the nation, an orchard, a grove of rare Franklinia trees, and frequent sightings of bald eagles, bluebirds, foxes, and other wildlife.
The farm's gardens include:
On September 4, 2020, AHS announced that it was putting the property up for sale to ensure the viability of their small national nonprofit, hit hard financially because of COVID-19 and the major expense of maintaining and operating River Farm.  The real estate listing estimates the property's value as between $18 million and $30 million.  Mount Vernon District Supervisor Daniel G. Storck and Paul Gilbert of NOVA Parks, among others, have been working to put together a purchase offer that could meet both AHS’s objectives and those of the Alexandria community, which hopes to see the privately-owned land purchased by local entities and transformed into a public park.