Yellow Flowers

• Taxicab-yellow petals encircling dark brown centers make black-eyed Susans (Rudbeckia hirta) attention-grabbing additions to the summer and fall garden. The sun- and shade-tolerant Aster family biennial stands 1 to 2 feet high, with narrow, bristly, lance-like green leaves. Butterflies and bees feed on its nectar, and birds on its ripened seeds. Black-eyed Susan does well near black walnuts and other juglone-producing trees. Fragrant columbine (Aquilegia fragrans) with its soft, yellow-and-white, honeysuckle-scented blooms perfume the spring garden. Its nectar-rich, spurred flowers open on nodding stems above airy clumps of lobed, green leaves. Fragrant columbine thrives in moist, organically rich soil and sun of partial shade.
  
  

Red Flowers

• Cardinal flower's (Lobelia cardinalis) brilliant red spires of hummingbird-attracting, spring-to fall blooms make the perennial a garden standout spring to fall. The 8-inch flower spikes well against the Cardinal flower's deep-green foliage. The up-to-6-foot perennial performs well in full sun or full shade, and moist or wet, rich loam. Coneflower (Echinacea) Firebird forms 2-1/2- to 3-foot mounds of large, lance-shaped green leaves. From late spring until late summer, a succession of bright red blooms crown its branching stems of deep-green, lance-shaped leaves. The blooms' drooping, ray petals surround reddish-brown, bristly conical centers. Firebird grows in sun or partial shade, but performs best in sun.
  
  

Blue Flowers

• Harebell (Campanula rotundifolia) fills early summer to early fall gardens. Its bell-like, blue-violet flowers nod on bending stems above clumps of green, grassy foliage. It attracts hummingbirds. This 4- to 15-inch high perennial grows in sun or shade. It likes dry, sandy soil. Dwarf bugleweed (Ajuga reptans) Dixie Chip brightens those dim garden spots with spreading clumps of variegated, green, white and pinkish-purple foliage. Mats of the tiny leaves stand only 2 to 4 inches tall. Dixie Chip's delicate, blue-purple bloom spikes emerge in May and June. This bugleweed grows in sun or shade with its best foliage colors occurring where it gets from three to four hours of daily sun.
  
  

Pink Flowers

• Cotoneaster's red berries brighten sun or shade.cotoneaster image by Alison Bowden from Fotolia.com
  
  Rock cotoneaster (Cotoneaster horizontalis var. perpusillus) transforms sunny or partially shady gardens with three seasons of color. The low, spreading shrub's long, layered, horizontal branches have glossy, green leaves. They make an effective backdrop for its tiny, light-pink, spring blooms and red, late-summer berries before deepening to reddish-purple in autumn. Follow rock cotoneaster's pink spring display with summer-blooming turtlehead (Chelone obliqua). It thrives in wet garden spots where other plants struggle. This 2- to 3-foot high perennial has erect stems of deep-green, tapering leaves. July and August see those stems topped with turtlehead's pink flower clusters. The blooms resemble snapdragons. Both plants thrive in sun or partial shade.