Sebastián Vidal was the best known director of the garden. He came to the Philippines in 1871 to work in the forestry service (Inspección General de Montes). He was director between 1878 and his death in 1889. His obituary in Popular Science Monthly described him as "practically a pioneer in the investigation of the Philippine flora". (In fact, a flora of the archipelago had been published by Francisco Manuel Blanco, but it was unsatisfactory). For his publications on Philippine flora, Vidal not only collected specimens, but also studied Malesian flora held in European herbaria, such as the Kew herbarium.
The American occupiers of Manila decided that the site was not suitable for a botanical garden and was more suitable for a public park. In 1913 it was renamed after John C. Mehan, who was in charge of Manila's parks and sanitation. The Mehan Garden was declared a historical site by the National Historical Institute in 1934.