The state of Oklahoma experiences a continental climate with sunny days, hot summers and colder winters. Oklahoma lies within the United States Department of Agriculture (USDA) Hardiness Zones 6 and 7. Oklahoma gardeners should select flowers according to appropriate zone, bloom time, flower color and intended use. Numerous types of flowers perform well in Oklahoma landscapes.
Propeller flowers (Alophia drummondii), also called pinewoods lilies, grow from corms and reach up to 2 feet in height. This perennial plant features pleated leaves and lavender to violet-blue flower clusters that appear from March through May. This iris family member (Iridaceae) prefers dry, sandy soils in sites that receive partial shade. Oklahoma gardeners often plant propeller flowers in wildflower meadows and prairies.
The standing cypress (Ipomopsis rubra), sometimes called the red Texas star, naturally occurs in fields and woods across Oklahoma. Showy flowers bloom from May through July, featuring vibrant red petals with yellow or orange spots. This phlox family member (Polemoniaceae) reaches between 2 and 4 feet in height. This biennial plant likes drier soils that receive at least partial sun. The standing cypress works well in hummingbird gardens and woodland gardens.
Blue curls (Phacelia congesta), also called fiddlenecks and caterpillars, usually grow in big colonies. Maturing between 12 and 36 inches tall, the blue curls plant prefers dry, rocky or sandy soils in partly to fully sunny locations. This waterleaf family member (Hydrophyllaceae) features raggedy leaves, brittle stems and coiled clusters of purple flowers. The bell-shaped blossoms appear from March through May. Oklahoma gardeners often use blue curls plants in butterfly gardens and meadows.
The fringed bluestar (Amsonia ciliate), also called the blue funnel lily, belongs to the dogbane family (Apocynaceae) and ranges from 15 to 24 inches in height. Flowers bloom from March through June, featuring clusters of star-shaped, light blue flowers with white centers. Fringed bluestar plants like well-drained, limestone or loamy soils in partially shady positions. These plants can be aggressive in fertile soils. Fringed bluestars perform well in perennial flowerbeds and woodland gardens.
American bellflowers (Campanulastrum americanum) feature spiked clusters of pale blue to violet-blue flowers with short, yellow stamens. These flowers bloom from June through August in Oklahoma gardens. This Campanulaceae plant family member ranges from 3 to 6 feet in height, and prefers moist, rich soils in partially shady positions. American bellflowers work well in hummingbird gardens, stream margins and woodland gardens.
The Indian paintbrush (Castilleja indivisa), sometimes called the Texas paintbrush, belongs to the snapdragon family (Scrophulariaceae) and reaches between 6 and 16 inches in height. This plant blooms from March through May, featuring long flower spikes of non-showy, green flowers held by showy, bright red flower bracts. Annual in Oklahoma gardens, these plants prefer dry, acidic soils in sunny positions. Indian paintbrushes should not be transplanted once established. Gardeners often use Indian paintbrushes in wildflower meadows, pocket prairies and butterfly gardens.