Connecticut is nestled in United States Department of Agriculture Plant Hardiness Zone 5, with a narrow strip of Zone 6 along its southern border. That means cold winters and warm summers, a fine environment for growing three seasons' worth of flowers. The challenge is fitting them all into available garden. Plan for spring bulbs, followed by a mix of summer and fall annuals and perennials, keeping in mind which will do best in sun, partial shade and shady conditions.
Plant beds of crocus and snowdrop for early April blooms in Connecticut. Follow with daffodils, hyacinths, and then tulips for a full spring of color and fragrance before the garden truly gets under way. After that, allium bulbs send up globes of flowers on tall stalks in summer, attracting hummingbirds and butterflies. Set bulbs with their widest end pointing down for best results.
Fill baskets with impatiens in partial shade for cascades of easy-care blooms in red, white, pink and lavender. Use bedding begonias for bordering trees, walkways and fences, or set out pots of single Rex begonias or New Guinea impatiens for a larger focal point. Boxes of petunias and geraniums will bloom all summer if you deadhead them when flowers are spent. Plant cosmos in sandy, coastal areas of Connecticut for sturdy tall stems capped with daisy-shaped flowers in pink, white and magenta. Try a sunflower or two in richer soil and enjoy yellow flowers up to the size of a dinner plate on stems 10 or more feet tall.
Plant bleeding heart for its heart-shaped blooms in April and May. As it fades, hosta fills in with broad, variegated leaves in shadier areas. For full sun and summer in Connecticut, day lilies, black-eyed Susan, Shasta daisy, coneflower and poppies add bursts of color and fresh foliage. Plant beds of iris, gladiola and canna for tall perennials, although you will have to dig up the canna bulbs and overwinter them indoors. Try lavender and yucca in drier, sandier soil in coastal areas. Cover yucca plants with leaf litter in fall to insulate roots against frost.
Interplant azalea with forsythia for a wild, graceful hedge of yellow in March followed by pink, white and scarlet in April. Rhododendron and hydrangea will follow with large, colorful blossoms in early summer. Hydrangea makes an excellent dried cut flower for fall. Plant roses but be prepared to do battle with aphids and rust. Train a healthy rosebush to climb a picket or wrought-iron fence, providing an old-fashioned look for your Connecticut yard.