Trees and shrubs are the major players in the framework of a garden.

Highly versatile perennials sharpen and fine tune that landscape.  Perennials define lines and shapes  through varying  heights,  from a tall ornamental grass to the ground-hugging creeping jenny.  Or form, through the mounding habit of Jerusalem sage or the cascading tendencies of some lantanas.  

Perennials also, of course, mold the garden with seasonal color and can contribute to a sense of style. Most are grown for their blooms, but several make contributions through their foliage.

Native columbines,  Louisiana phlox and fragrant dianthus bloom in early spring in the cottage garden.  Shasta daisies and daylilies hang around spring into summer.  Numerous salvias begin a long stint in spring that comes to a close with frost in the native plant garden. The tubular blooms of the hamelia draw hummingbirds in the fall. Red yucca and agaves are workhorses in a xeriscape. Hostas and toadlilies prefer the moist, partial shade of the woodland garden.

Perennials are those plants that linger in the garden, returning year after year like old friends. There are perennial bulbs and rhizomatous plants (daffodils, irises, gingers and rainlilies), root-hardy vines (Carolina jessamine), herbs (rosemary) and ornamentals ( coneflowers). 

Some carry on longer than others. Ligularia, grown for its glossy round leaves dappled with yellow,  is likely to stick around for years in the shade.  Winter-and spring-flowering German primroses are often shorter lived.

Study your garden’s microclimates so that you can give perennials the proper setting. There are numerous choices not only for sun, but for shade.  Our climate extremes are notorious, so build a raised, well-draining bed of organically enriched soil for those perennials such as Blue Princess and Homestead verbena that hate soggy conditions that can occur during prolonged rainy periods.  

Plant variegated sweetflag (Acorus calamus variegatus) and spider lilies (Hymenocallis) in those shady, wet spots. And remember, if a perennial does not thrive where initially planted,  don¹t be afraid to move it.

When searching for perennials for Houston area summer gardens, look for those that will tolerate long stretches of humid heat and survive with little rain. There are a surprising number that will provide months of color. Among the drought- and heat-tolerant troopers;   lantana;  salvias; easy, long-flowering bulbine;  light-hearted gaura; magenta, pink and white summer phlox; Goldsturm and Indian Summer rudbeckias; purple coneflowers; the graceful ornamental grasses, which come in varying heights; butterfly weed; and plumbago, in baby  blue or white. Yellow bells (Tecoma stans) is a perennial that can reach shrub proportions here and produce yellow blooms late spring to frost. Remove the beanlike seed pods to encourage more blooms. This plant looks good pruned into a tree shape with blue plumbago billowing around its base.

Some perennials are evergreen, but many go dormant at some point during the year. This rest period may be in winter or summer. Lantana and rudbeckias, for example, stop performing when the weather turns cold. Mulch them for the winter; prune them before new growth starts in spring.  Columbines, on the other hand,  will virtually disappear in summer. When the weather cools, new foliage will sprout. When perennials rest, carefully tuck in annuals for color.