There are not a lot of perennials in bloom in the garden in May. The first blossoms I see are Periwinkles in early May. This is a ground cover that I have around the base of many of the trees in the yard. Usually Purple Rock Cress blooms early in the month also. In the middle of the month Primrose, Bleeding Hearts, and striped Moss Phlox are in bloom. Moss Phlox and Purple Rock Cress are both low growing plants, they spread well and will trail over rocks and rock walls. The Purple Rock Cress blooms for six or seven weeks and if trimmed back will rebloom later in the season. My earliest Iris also blooms in early May. My smaller Candytufts will bloom in early May. At the very end of the month my larger Candytuft opens. This plant the is over three feet in diameter and quite spectacular. Fall planted bulbs such as Daffodils, Tulips, or Hyacinths offer additional color in early May. Last winter my pansies survived and were a great addition to the garden in late May.