In 1886, the Edisons built a winter home in Fort Myers, Florida. Edison also established a laboratory on the estate and carried out his last grand experiment there in the late 1920s. To lessen U.S. dependence on foreign sources of natural rubber, Edisons friends Henry Ford and Harvey Firestone encouraged him to find a domestic substitute for rubber.In a search reminiscent of his hunt for the light bulb filament, Edison tested thousands of plant samples. By 1930, he had decided that goldenrod held the most potential as a rubber producer. But Edison was 80 years old by then and in poor health. He never completed his rubber experiments.