The boulevard of the show is adorned with four large installations highlighting the ways container gardens can be made appealing all year long. In “Spring” we see hyacinths and tulips. “Summer” sports the warm earth tones of grasses and variegated ivy. With “Fall” its mums, kale and ornamental cabbages. And “Winter” — a constellation of evergreens, gold mop cypress and eucalyptus — reminds us gardening doesn’t end with the first snowfall.