(DC) (United States Botanic Garden) The annual holiday display “Season’s Greenings” features model trains in the gated outdoor gardens, festive lights throughout the Garden, and the poinsettias, holiday decor, and D.C. landmarks made from plants inside the Conservatory. On the lawn in the gated outdoor gardens, G-gauge model trains circulate from 10:00-5:00 daily through displays of pollinators made from plant ...