Originally called Cobbling Rock Farm, the Lasdon estate was purchased by William and Mildred Lasdon in 1939. Known for establishing a major pharmaceutical company and for their philanthropic endeavors, the Lasdon family used the estate as a country retreat and had a full-time staff to maintain its buildings and grounds. William Lasdon had a keen interest in horticulture and, through his world traveling, imported many tree specimens to his estate.

Situated off Route 35 in Somers, Lasdon is bounded on the south and east by New York City watershed property, the Amawalk River and the county's own Muscoot Farm, and on the west by the Mildred D. Lasdon Bird and Nature Sanctuary. This 22-acre preserve was donated to the county in 1976 by William Lasdon and named for his wife. A self-guided trail affords views of many species of birds and as many as 20 distinct types of warblers can be observed there during migration.

In 1986, Westchester County purchased the property from the Lasdons for $4.2 million as part of the county's continuous effort to obtain and preserve open space. During that summer, the motion picture "The Secret of My Success" was filmed within the formal gardens, pool and main house. Much of the formal grounds remain as they were originally designed, and Westchester County has been developing and embellishing the collections on the property.

Today, Lasdon Park is the horticultural hub of Westchester County. The Colonial Revival-style pavilion main house provides offices for groups such as the Ninth District Federated Garden Clubs and the Westchester Tree Protective Association, and is home to the Lasdon Horticultural Library. The house also consists of meeting rooms for horticultural workshops and botanical art classes, a gallery for art exhibits and serves as the headquarters for the Friends of Lasdon Park and Arboretum volunteer organization. The pool house has been converted into the Gift Shop (currently closed), an information center and plant shop that offers plants and gardening-related items for sale, and is staffed by members of the Friends of Lasdon.