On Saturday, when the Madoo Conservancy opens for the 2019 season, it will also celebrate 25 years as a public garden in Sagaponack with “Madoo: A History in Photographs.”Organized by Perry Guillot, a Southampton landscape architect who lived at Madoo from 1987 to 1994, it will include photographs, book and magazine features, and artworks based on the garden designed by Robert Dash, the conservancy’s founder, who died in 2013.Sharing the winter studio with a group of six close friends for seven summers, Mr. Guillot said, “Madoo was our private Eden of lush beauty and ridiculous fun.” In comparison to the lemming-like adherence to the dictates of a select few that most gardens represent here and in other wealthy communities, he recalls “how incredibly personal Bob’s garden was and still is today.”The photographs span a period from 1970 to 2018 and show the progression of the open fields into an “ever-evolving joyful mashup of planting combinations that only Bob could explain,” according to Mr. Guillot. The photographers include Dash, Hans Namuth, Mick Hales, Derek Fell, Rameshwar Das, and others. In evidence in the photographs will be some of his notable close friends and acquaintances. Dash saw Madoo as a record of his gesamkunstwerk, a German term for a complete artwork that brings together all of the elements of one’s creative output, be it painting, gardening, or poetry.His early gestural botanical studies will be included and on public view for the first time. They provide a foreshadowing of his more abstract works to come, such as the “Florilegium” series, exhibited at Madoo in 2017. Also on view will be Dash’s “Fire Screen,” a double-sided painting on a fire screen from the house. The garden theme of the painting underlines the links the artist saw between house and garden, garden and art. The piece became “an integral part of defining the interiors at Madoo,” according to the conservancy. The exhibition will be on view during Madoo’s public visiting hours, Fridays and Saturdays from noon to 4 p.m. through July 27. This exhibition is free and open to the public. The gardens will be open through Oct. 12.