You are here: Home / Plant Profiles by Category / Perennials

Perennials

Oklaoma Proven! logo.jpg

 

Oklahoma Proven is a plant promotion program coordinated by faculty in the Department of Horticulture and Landscape Architecture at Oklahoma State University. The goal of the program is to recommend plants well-adapted for use across Oklahoma.

 

 

Perennial for 2017

Milkweed

Asclepias species

Asclepias species are the milkweeds. Native to America they are well adapted to many soil types. Best known as the host plant for monarch butterflies, the milkweeds have gained a lot of attention lately and efforts across the country to reestablish lost habitat to help save the declining monarch population is taking the front stage for gardeners, butterfly enthusiasts, and conservationists. Butterfly milkweed, Asclepias tuberosa, is the most popular of Asclepias species with bright orange to yellow-orange flowers on upright stems growing 1 to 3 feet tall. In fact, butterfly milkweed has been named the Perennial of the Year in 2017 by the Perennial Plant Association. Milkweeds in general grow in average, dry to medium, well-drained soils in full sun and are very drought tolerant and have no serious pest problems. Grow in native plant gardens, wild gardens, meadows, naturalized areas, perennial borders, and cottage style gardens.

  • Exposure: Sun, part shade
  • Soil: Tolerates about any soil
  • Hardiness: USDA Zone 4-10
2017 Asclepias

 

 

 

Perennial for 2016

Sedges

Carex species

Sedges belong to the genus Carex, which is a genus of many species, most from wet areas such as bogs. Sedges have triangular, grass-like stems and panicles of short flower spikes. Foliage can be evergreen or deciduous and colors range from green, brown/rust, golden, blue, to variegated. Sedges are grown in groups or masses, as a lawn substitute, in naturalized areas, perennial borders, and habitat restoration. They are grown particularly in shady areas where the variegated varieties really shine. Some require damp or wet conditions while others are relatively drought tolerant.

  • Exposure: Full sun to part or full shade
  • Soil: Dry to wet soils
  • Hardiness: USDA Zone 3-10

 

 

 

Perennial for 2015

Volcano® series, Garden Phlox

Phlox paniculata

Phlox Volcano® is more compact, fragrant, and powdery mildew tolerant than other garden phlox types. Plants develop sturdy stems, 24-28” tall, with deep green leaves and an abundance of large flowers that appear from June to September if plants are cut back after initial bloom. Flower colors range from red, pink, ruby, white, lavender, and purple; flowers may also have eyes of pink, red, or white or are bicolored such as with Lilac Splash. It doesn’t mind most soils, but needs well drained soil; irrigate with soaker or drip irrigation to keep foliage dry. Full sun is the best exposure for Volcano phlox, but it will grow in part shade; too much shade and poor air circulation increases chances of mildew developing, though it still does not seem to inhibit flowering. Once established, phlox is very adaptable. It is grown as an accent, in groups, or masses. It also works well in native plant gardens, wild gardens, meadows, naturalized areas, perennial borders, and cottage style gardens. Butterflies and hummingbirds are attracted to the colorful, fragrant flowers.

  • Exposure: Sun, part shade
  • Soil: Tolerates about any soil
  • Hardiness: USDA Zone 4-10

 

 

 

Perennial for 2014

Switchgrass

Panicum virgatum cultivars

Switchgrass is native throughout North America and is a dominant species of the tallgrass prairies. It doesn’t mind most soils and actually grows well in wet and dry locations. Full sun is the best exposure for switchgrass, but it will grow in part shade; too much shade or rich soils may result in floppy plants. Switchgrass is a warm-season perennial, growing largely as a bunchgrass 3 to 6 feet tall, but may spread by rhizomes or self-seeding. Switchgrass has an upright, stiff form overall. Flower panicles are open, lacy sprays, with a purplish tint that persist into the winter. Leaf color is generally medium green turning yellow, sometimes with orange tints, in fall; however, several cultivars exist – ‘Heavy Metal’, has metallic-blue foliage, ‘Northwind’ is bluish-green, ‘Shenandoah’ has foliage with dark purple tips, and ‘Cheyenne Sky’ turns wine red. Winter color is tan to beige. Once established, switchgrass is very drought tolerant. It is grown as an accent, in groups or masses and can be effective as a screen. It also works well in native plant gardens, wild gardens, meadows, naturalized areas, as well as rain, water, and bog gardens.

  • Exposure: Sun, part shade
  • Soil: Tolerates about any soil
  • Hardiness: USDA Zone 5-9

 

 

 

Perennial for 2013

Catmint

Nepeta x faassenii 'Walker Low's'

Walker’s Low Catmint was the Perennial Plant of the Year in 2007 and is an easy to grow, pest free perennial. This hybrid Nepeta develops into a mound of aromatic, grayish green foliage. Lavender-blue flowers appear in spring and continue to bloom if properly pruned by trimming after initial flowering. Walker’s Low grows 1 to 2 feet high and 1 ½ to 3 feet wide and can be used as edging or in a border, herb or rock garden, naturalized area, as groundcover, or is quite attractive spilling over the edge of a wall. Nepeta attracts bees and butterflies. It also tolerates some shade, dry, rocky soil, and is quite drought and deer resistant.

  • Exposure: Sun, part shade
  • Soil: Moist, well-drained
  • Hardiness: USDA Zone 3-8

 

 

 

Perennial for 2012

Arkansas Bluestar

Amsonia hubrichtii

Arkansas bluestar is native to eastern Oklahoma and Arkansas, but does well throughout the state. It is tolerant of moist soils and is quite drought tolerant once established. Flowers are sky blue, star shaped and develop in clusters at the end of each branch in early spring. Leaves are needle-like on upright stems that sway in the breeze providing a soft, wispy appearance; foliage is bright green in summer and then in fall, seemingly overnight, it explodes to a golden yellow. Amsonia grows to 3 feet high. Plant in masses for best effect. Can be used in mixed borders, meadows, native gardens, and open woods.

  • Exposure: Sun, part shade
  • Soil: Moist, well-drained
  • Hardiness: USDA Zone 4-9

 

 

 

Perennial for 2011

Giant Coneflower

Rudbeckia maxima

Giant coneflower is native to eastern Oklahoma, but does well throughout the state. It is tolerant of moist soils and is quite drought tolerant once established. Giant coneflower has silvery-blue foliage. Flowers have bright yellow ray flowers that dangle from a large, upright, dark brown cone on stems that reach 5-6 feet high. Giant coneflower blooms in early summer but deadheading the spent blossoms will encourage another flush of blooms in late summer. Plant in masses for best effect. Can be used in mixed borders, meadows, native gardens, and open woods. This species makes a strong vertical statement in the landscape.

  • Exposure: Sun, part shade
  • Soil: Moist, well-drained
  • Hardiness: USDA Zone 4-8

 

 

 

Perennial for 2010

Toad Lily

Tricyrtis hirta

Toad lilies are known for their very unique flowers. Flowers are pale lilac with dark purple spots that appear on upright arching stems late summer to early fall when many other plants are beginning to wind down. Though flowers are quite unique, they are small so place toad lily in a spot where the flowers can be appreciated up close. The plant grows 2’ to 3’ high and about 2’ wide with bright green leaves. They are excellent for the woodland garden as understory plants where they will be protected by shade. Toad lily is easy to grow, resistant to deer, somewhat drought tolerant, but grow best in moist soils and will even tolerate wet conditions. Several cultivars with varying flower colors are available.

  • Exposure: Shade, partial shade
  • Soil: Moist, well-drained
  • Hardiness: USDA Zone 4-8

 

 

 

Perennial for 2009

Mexican Feather Grass

Nassella tenuissima

Mexican feather grass is a fine textured clumping perennial that waves its silvery flowers in the slightest breeze. It is drought tolerant and tough despite its refined appearance and forms a clump almost two feet tall and three feet wide as the leaves arch to the sides. It tolerates a wide variety of conditions, but prefers well-drained soils and does not like to be cut to the ground in spring like other grasses. Remove only the top third of the plant to rejuvenate. It is native to prairies in Texas, New Mexico, and south to central Mexico and may reseed in the garden.

  • Exposure: Full sun to part shade
  • Soil: Well-drained
  • Hardiness: USDA Zone 7

 

 

 

Perennial for 2008

Hellebore

Helleborus

Hellebores, also known as Lenten Rose, belong to a genus of mostly evergreen herbaceous plants that are prized for their ability to flower in late winter. The flower stalks rise out of the leaf litter or through the snow to display nodding flowers that range in color from green to white, yellow, or even purple with some cultivars producing spotted flowers. Recently hybrids have been selected for outward-facing flowers and brighter colors increasing their garden value. Hellebores are tough plants requiring little special care other than shade and pruning of old foliage. They are excellent for the woodland garden as understory plants where they will be protected by shade.

  • Exposure: Shade
  • Soil: Moist, well-drained
  • Hardiness: USDA Zone 6

 

 

 

Perennial for 2007

Evening Primrose

Oenothera macrocarpa 'Comanche Campfire'

This species of Evening Primrose is native to western Oklahoma and ‘Comanche Campfire’ was selected for its ability to produce beautiful yellow flowers above red petioles and silver foliage. It is touted as a xeriscape perennial since it thrives in well-drained soil and, once established, requires little moisture. As a low-growing, clumping perennial, ‘Comanche Campfire’ reaches a height of 15 to 18 inches and spreads to two feet. Use it in a rock garden or along the edge of a perennial bed.

  • Exposure: Full sun
  • Soil: Well-drained
  • Hardiness: USDA Zone 4

 

 

 

Perennial for 2006

Golden Jubilee Anise Hyssop

Agastache foeniculum 'Golden Julibee'

‘Golden Jubilee’ is a cultivar of the North American native commonly known as anise hyssop. It was selected for its chartreuse foliage, was named to commemorate HM Queen Elizabeth II’s golden jubilee, and was the 2003 All-America Selections flower award winner. Reaching 2' tall and 1' wide, ‘Golden Jubilee’ produces light purple flower spikes from early summer to fall. Although a perennial, it will reseed in your garden and the new plants will also be golden. As an added bonus, brushing against the foliage releases the plant’s licorice scent.

  • Exposure: Full sun
  • Soil: Moist, well-drained
  • Hardiness: USDA Zone 6

 

 

 

Perennial for 2005

Perennial Plumbago

Ceratostigma plumbaginoides

Perennial plumbago is a neat, well-behaved plant that grows 8" to 12" high and spreads to 18" making it welcome at the front of a mixed border or massed as a ground cover. The terminal clusters of blue flowers appear from summer through fall when the foliage turns a bronze-red before going dormant for the winter. It is best to use perennial plumbago in a well-drained soil and to cut old stems to the ground each spring for vigorous re-growth.

  • Exposure: Partial shade to full sun
  • Soil: Well-drained
  • Hardiness: USDA Zone 5

 

 

 

Perennial for 2004

Autumn Sage

Salvia greggii 'Pink Prefernce'

‘Pink Preference’ is a cultivar of Autumn Sage that was selected for its bright pink flowers. Like the species, it is a heat and drought tolerant perennial that starts blooming in the spring but blooms most in the autumn as other flowers in the garden start to fade. It forms a two to three foot mound and attracts hummingbirds and butterflies to the garden. Pruning to six inches high each spring will help keep Autumn Sage dense and full.

  • Exposure: Full
  • Soil: Well-drained
  • Hardiness: USDA Zone 6

 

 

 

Perennial for 2003

Japanese Painted Fern

Athyrium nipponicum

Japanese Painted Fern is a deciduous perennial growing to twelve inches tall. It can be used in shaded perennial gardens or massed as a ground cover. Cultivars are available, each with its own pattern of red and silver variegation.

  • Sun Exposure: Part to full shade
  • Soil: Moist, well-drained
  • Hardiness: USDA Zone 4

 

 

 

Perennial for 2002

Magnus Purple Coneflower

Echinacea purpurea 'Magnus'

Magnus Purple Coneflower is known for its rose-colored flowers that appear in early summer and sporadically until frost. Magnus is a clump forming perennial that grows to 2 - 3 feet tall. Use this heat and drought tolerant perennial in a native plant garden, perennial border, or as a cut flower.

  • Sun Exposure: Full sun to light shade
  • Soil: Well-drained
  • Hardiness: USDA Zone 3

 

 

 

Perennial for 2001

Siskiyou Pink Gaura

Gaura lindheimeri 'Siskiyou Pink'

Gaura is a drought-tolerant perennial that thrives in the heat and humidity of the South. Although the species produces white flowers, the cultivar ‘Siskiyou Pink’ has bright pink flowers that appear on airy, 3- to 4-foot-tall sprays early in the spring. Blooming will continue until fall if old flower spikes are removed.

  • Sun Exposure: Full sun to partial shade
  • Soil: Well-drained
  • Hardiness: USDA Zone 5

 

 

 

Perennial for 2000

Homestead Purple Verbena

Verbena canadensis 'Homestead Purple'

Homestead Purple’s deep purple flowers and trailing habit make it perfect for hanging baskets, as a ground cover, or as the foreground of a mixed border. This North American native will bloom from spring to frost, slowing down only slightly during the hottest months.

  • Sun exposure: Full
  • Soil: Moist, well-drained
  • Hardiness: USDA Zone 4

 

 

 

Perennial for 1999

Powis Castle

Artemisia 'Powis Castle'

With dense mounds of lacy silver foliage, this perennial reaches a height of 3’ and remains evergreen during mild winters. It is prized for its feathery foliage and its drought tolerance.

  • Sun Exposure: Full sun to part shade
  • Soil: Well-drained
  • Hardiness: USDA Zone 5