Genus Common Name Blooming Time Achillea Yarrow June-July Alchemilla Lady’s Mantle June-July Allium Wild Onion May-Aug Alcea Hollyhock (biennial) July Aquilegia Columbine May-June Arabis Rock Cress April Asclepias Milkweed; Butterflyweed July Aster Aster Sept–Oct Astilbe Astilbe June-Aug Aurinia Basket-of-Gold April Baptisia Wild Blue Indigo June Boltonia Boltonia Aug-Sept Campanula Bellflower June-July Chelone Turtlehead Aug-Sept Clematis