Boston Flower and Garden Show March 22-26 Seaport World Trade Center Boston. ‘Superheroes of the Garden’. Mass Masters Gardeners Assn plans to showcase ‘Gardeners and their Tools’ as our superheroes of the garden. Look for our rain barrel in the MMGA booth. The exhibit will focus on educating and engaging the public about smart watering techniques, water conservation, and best gardening practices. And the Great American Rain Barrel will be raffled off.