The Brooklyn Botanic Garden has been labeled one of New York City's greatest treasures. It has at least 20 different gardens, pavilions, exhibits, collections and even museums. The lilacs are especially popular in April and May when their scent fills up the air. In late April, the bluebells burst into flower and create a captivating woodland spectacle. The tree peonies and their marvelous aroma bloom in April and May as well.