According to the USDA Plant Hardiness Zone Map, perennials in zone 7 are hardy to 0 to 10 degrees Fahrenheit. Cities in zone 7 include Oklahoma City, Oklahoma; South Boston, Virginia; Little Rock, Arkansas; and Griffin, Georgia. The Perennial Plant Association has chosen many zone 7 plants for its Perennial Plant of the Year Program. These plants are chosen because they are suitable for many zones, low maintenance and easily propagated, and provide interest throughout multiple seasons.
Arkansas amsonia (Amsonia hubrichtii) was named the 2011 Perennial of the Year by the PPA. It brings beauty to the garden from late spring to early fall with light-blue, star-shaped flowers on feathery stalks. In fall the plant turns golden. When it is planted en masse it is exceptionally attractive. It grows up to 3 feet tall and as wide in a mound. This perennial is not fussy; it prefers well-drained soil and will grow with little water. It grows in partial shade to full sun. It is a North American native that is hardy in zones 4 through 9.
Blue False Indigo
Blue false indigo is a spring flowering shrub that's also known as wild indigo and baptisia (Baptisia australis). It blooms in lavender on stalks that grow up to 4 feet tall and as wide. It starts growing slowly but within three years it will flourish and reach full size. It thrives in full sun and likes well-drained soil; it is drought tolerant after it's established. It is hardy in USDA zones 3 through 9.
Golden Hakone Grass
Golden hakone grass is an ornamental perennial that is used as a ground cover, in mass plantings or in containers. It is low maintenance; you'll need to cut dead leaves back once a year in late winter. The golden leaves have green stripes. It likes partial shade in warm climates, or more sun in cool regions. It grows best in well-drained soil. It is hardy in USDA zones 5 through 9.
Geranium Rozanne (Rozanne cranesbill geranium) blooms for a long period of time with almost 3-inch violet-blue flowers and white centers. The perennial is known for its nonstop flowering from spring through early fall. It grows up to 20 inches tall on mounds, and up to 2 feet wide. It will grow best in full sun to partial shade and prefers well-drained soil. It is heat and drought tolerant and hardy in USDA zones 5 through 8.