To lessen your overwhelm when you go to the garden centre, it helps to have some principles of design and organization under your belt. Often we get dazzled by what perennial plants are currently in bloom, and we end up wanting one of those, and one of those because of the colourful blooms.
But colour isn’t everything. Good garden design takes into account the shapes of perennials. Remember that perennials bloom for only about three weeks, so the foliage and overall shape have to have season-round attractions. A variety of plant shapes gives the garden a sculptural quality, provides contrast and visual interest. There are five key shapes in perennials. Remember that odd groups of three, five or seven are better than just one plant alone.
Spikes: Delphiniums, Foxgloves, Hollyhocks. Tall Bearded Iris, Lupins, Campanula Persicifolia, Alliums, Foxtail Lilies, Liatris, Feather reed grass (Calamagrostis), Snakeroot (Actaea racemosa) and many taller Veronicas, like “Purpleicious”.
Mounded: This is a huge category, just make sure you don’t choose all plants for your garden from this group. Johnson’s Blue, Rozanne, and other Geraniums, Lavender, Euphorbia Polychroma, Hostas (not all, some have a fountain shape, like “Praying Hands”) Lady’s Mantle, Chrysanthemum, Autumn Joy Sedum, Pulmonaria, Matricaria, Dwarf Asters, Dianthus, Fleabane, Gaillardia and Candytuft.
Prostrate: (Groundcovers) Periwinkle, Creeping Thyme, Sedum Acre, Hens and Chicks, Ajuga, Sweet Woodruff, Phlox Subulata, and Aubretia.
Fountain: Daylilies, Ornamental Grasses, (Miscanthus sinensis) ‘Morning Light’, Crocosmia, Peonies, Bleeding Heart, (Dicentra) Some Hostas, (ie “Sagae” “Krossa Regal” “Green Fountain”)
Fan: Meadow Rue, Goats Beard, Joe Pye Weed, Goldenrod. (Solidago)