SINGING THE BLUES
By Dr. Leonard Perry, Extension Professor
University of Vermont
Blue is probably the least common color in the garden. While not common among flowers, it is even less common among other plant parts.
Of course, there are the blue leaves of rue, some hostas, some ornamental grasses, and blue spruce. And there are blue fruits on some perennials, such as the Solomon's Seal (Polygonatum), vines like the porcelain berry (Ampelopsis), and shrubs like the arrowwood (Viburnum).
Blue flowers are more often seen, and have more vivid colors, in cool northern climates, such as in Europe and increasingly in this country. Being an uncommon color, they can add variety to a garden. Or they can be used to evoke the perception of distance, the feeling of relaxation, or mirror "blue" moods. There are probably more blue flowers than you might imagine for your garden.
In his recent book, A Book of Blue Flowers, Robert Geneve lists 44 main families of ornamental plants containing blue flowers. Some families contain more, such as the Aster, Borage, Bellflower, Mint, Lily, Snapdragon, and Nightshade families. But not all members of a genus are normally blue.
A clue that it's blue might be that the species name is caerulea, cyanea, or azurea. There are many cultivars among the various families with names such as 'Heavenly Blue,' 'Sky Blue,' or 'Blue Star.' Keeping this in mind--that not all members of a genus are usually blue--here are some examples of various plant groups and uses.
For annual bedding plants you might consider the Ageratum (floss flower) or Torenia for low clumpers; Scaevola (blue fan flower), petunia, or verbena for low spreaders; sweet pea for a climber; and tall ageratum or mealy-cup sage (Salvia) for tall backgrounds.
Looking for a blue-colored flower for a hanging basket? Consider Browallia, Lobelia, petunia, or Scaevola. For specimen plants or containers consider Agapanthus, hydrangea, or Plumbago.
Vines with blue flowers include clematis, morning glory, and for warm climates, wisteria and passion flower. For cut flowers you might use tall ageratum, the bulb Camassia, Eustoma (prairie gentian), iris, lavender, statice, lupine, scabiosa, or Perovskia (Russian Sage).
Bulbs include Alliums (ornamental onions), Camassia, crocus, hyacinth, Muscari (grape hyacinth), or iris. Some irises also may be used around ponds as can some water lilies and pickerel weed (Pontederia).
Some perennials for shade, in addition to the blue foliage hosta cultivars (often with "blue" in the name) include Ajuga (bugleweed) and Vinca ground covers; forget-me-not (Myosotis), Jacob's ladder (Polemonium), some primroses, and many lungworts (Pulmonaria). Perennials for sun in spring include Ajuga, columbine, Baptisia, Camassia, and Symphytum.
Amazed by the number of blue flowers? The list continues with summer perennials for sun like Agastache, Amsonia, Campanula, Centaurea, Delphinium, Echinops, Geranium, Iris, Lavandula, Limonium, Lupinus, Nepeta, Perovsia, Phlox, Platycodon, Salvia, Scabiosa, and Veronica, among others. For autumn bloom, try blue asters and Caryopteris.
This growing season, why not start singing the blues in your flower garden by incorporating some blue-flowered cultivars in existing beds. Or design a monochromatic blue bed for all-season flowering.