USDA Zone 6: Perennials

Aster or Hardy Aster (Aster sp.)
Astilbe (Astilbe sp.)
Baby's breath (Gypsophila paniculata)
Balloon flower or Chinese bellflower (Platycodon grandiflorus)
Banana, hardy (Musa basjoo)
Barrenwort (Epimedium)
Basket-of-gold (Aurinia saxatilis)
Beardtongue, penstemon (Penstemon)
Bear's breeches (Acanthus sp.)
Bee balm, Oswego tea (Monarda sp.)
Begonia, hardy (Begonia grandis)
Bellflower (Campanula sp.)
Bergenia (Bergenia sp.)
Black-eyed Susan (Rudbeckia sp.)
Blanket flower (Gaillardia x grandiflora)
Bleeding heart (Dicentra)
Blue fescue (Festuca glauca)
Bluestar, or amsonia (Amsonia tabernaemontana)
Boltonia (Boltonia asteroides)
Brunnera (Brunnera macrophylla)
Bugbane (Cimicifuga)
Bugleweed (Ajuga sp.)
Bugloss (Anchusa)
Calamint, lesser (Calamintha nepetoides)
Campion, catchfly (Lychnis)
Candytuft (Iberis)
Cardinal flower (Lobelia)
Chamomile (Anthemis)
Chrysanthemum, Mum (Chrysanthemum)
Cinquefoil, Nepal (Potentilla nepalensis)
Colewort (Crambe cordifolia)
Columbine (Aquilegia)
Coneflower (Echinacea sp.)
Coral bells, alumroot (Heuchera)
Coreopsis, common (Coreopsis grandiflora)
Coreopsis, threadleaf, tickseed (Coreopsis verticillata)
Cranesbill (Geranium)
Crocosmia (Crocosmia crocosmiiflora) hybrids
Daylily (Hemerocallis sp.)
Delphinium (Delphinium)
Dianthus, pink, carnation (Dianthus)
Feather reed grass (Calamagrostis sp.)
Fleabane (Erigeron)
Foamflower (Tiarella cordifolia)
Foxglove (Digitalis)
Gas plant (Dictamnus)
Gayfeather (Liatris)
Globeflower (Trollius)
Goatsbeard (Aruncus sp.)
Golden-ray (Ligularia)
Hakone grass, variegated Japanese reed grass (Hakonechloa macra)
Hellebore (Helleborus)
Hibiscus, rose mallow (Hibiscus moscheutos)
Hibiscus, swamp (Hibiscus coccineus)
Hosta (Hosta sp.)
Hyssop, sunset (Agastache rupestris)
Inula, swordleaf (Inula ensifolia)
Iris, bearded (Iris hybrids)
Iris, crested (Iris cristata)
Iris, Dutch (Iris xiphium)
Iris, Japanese (Iris ensata)
Iris, Louisiana
Iris, reticulated (Iris reticulata)
Iris, Siberian (Iris sibirica)
Lady's mantle (Alchemilla)
Lamb's ear, betony (Stachys)
Lavender, common or English (Lavandula angustifolia)
Lavender cotton (Santolina chamaecyparissus)
Leopard's-bane (Doronicum)
Lily (Lilium)
Lily, Canada (Lilium canadense)
Lily, gold band (Lilium auratum)
Liriope, lilyturf (Liriope muscari)
Lupine (Lupinus)
Maiden grass, Eulalia (Miscanthus sp.)
Meadow rue (Thalictrum)
Meadowsweet (Filipendula)
Onion, flowering (Allium)
Pearly everlasting (Anaphalis)
Peony (Paenoia)
Phlox, garden (Phlox paniculata)
Pincushion flower (Scabiosa)
Plumbago, leadwort (Ceratostigma)
Poppy (Papaver)
Primrose (Primula)
Red-hot poker (Kniphofia uvaria)
Sage, bog (Salvia uliginosa)
Sage, common (Salvia officinalis)
Salvia, perennial (Salvia x superba)
Sage, Russian (Perovskia atriplicifolia)
Sandwort (Arenaria)
Sea holly (Eryngium)
Sea lavender (Limonium)
Solomon's seal (Polygonatum)
Speedwell (Veronica)
Sunflower (Helianthus)
Sunflower, false (Heliopsis helianthoides)
Sunflower, swamp or narrow-leaf sunflower (Helianthus angustifolius )
Thrift, moss pink (Phlox subulata)
Thrift, sea pink (Armeria)
Thyme (Thymus sp.)
Valerian, red (Centranthus)
Verbena (Verbena)
Violet (Viola)
Windflower (Anemone)
Wormwood (Artemisia)
Yarrow (Achillea)