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Oklahoma Proven Celebrates 25 Years of Assisting Landscape Decisions

Sunday, January 14, 2024

For a quarter of a century, the Oklahoma Proven program has helped guide gardeners in making smart decisions regarding which trees, shrubs, perennials and annuals are well adapted to an Oklahoma landscape.


Oklahoma Proven began in 1999 as a plant evaluation and marketing program designed to help gardening enthusiasts select the best plants for their gardens and landscapes. The plants deemed worthy of the Oklahoma Proven title have been shown to tolerate the growing conditions found throughout Oklahoma. Choosing these well-adapted plants can help lead to greater gardening success.


Here are the 2024 Oklahoma Proven selections. Color photographs of all 25 years of selections can be found on the Oklahoma Proven website. 


Tree: Ceris, Redbud species and improved cultivars. Found throughout North America, Europe and Asia, this small-to-medium deciduous tree can grow to about 20 to 30 feet tall or as a multi-stemmed large shrub. The eastern redbud is Oklahoma’s state tree. The redbud species doesn’t have serious insect or disease problems. It grows well in USDA Hardiness Zones 4-9 and prefers moist, well-drained soil. While part shade is best, it can tolerate full sun.


Shrub: Corylus avellana ‘Contorta’, is also known as Harry Lauder’s Walking Stick, Contorted Filbert or Corkscrew Hazel. This plant adds visual interest to the landscape due to its curly, twisty stems and foliage. The contorted stems are especially of interest in the winter after the leaves have fallen. Late winter flowers can also add winter interest. The shrub is multi-trunked and grows to about 8 to 10 feet tall. Some cultivars have been developed, including dwarf cultivars, which are great for small spaces or containers. Corylus avellana prefers full sun to part shade, medium moisture and is rated for USDA Hardiness Zones 3-9.


Perennial: Vernonia lettermanii, Narrow-leaf Ironweed. Native to rocky outcrops, floodplains and river scours in west-central Arkansas and adjacent areas of Oklahoma, this is an upright, clump-forming herbaceous perennial. Featuring finely textured, thin and narrow leaves, this plant grows about 2 feet tall with an equal spread. Bright purple flowers appear in mid to late summer. Gardeners who enjoy hummingbirds, butterflies and other pollinators in the garden won’t go wrong with this selection. This plant grows well in medium to dry, well-draining soil in full sun. Once established it can withstand occasional flooding and drought conditions. Mass plantings create an eye-catching, late-season display. It’s a great choice for USDA Hardiness Zones 4-9.


Annual: Zinnia hybrida Profusion Red Yellow Bicolor. Whether planted in full sun or part shade, this Oklahoma Proven selection starts the season with a bold red center ring surrounded by golden-yellow outer petals. The aging flowers morph into soft shades of apricot, salmon and dusty rose throughout the season. This plant was a hit with visitors to the trial garden. Soil should be moist and well-drained. Designed for USDA Hardiness Zones 4-9, this plant also attracts pollinators.


Collector’s Choice: Asimina triloba, Pawpaw. The Collector’s Choice selection is geared toward the more adventurous and seasoned gardener. The Pawpaw is a deciduous, native, understory tree in the Annonaceae family. It grows well in conditions from deep shade to full sunlight. It will tolerate occasional moist conditions but prefers good drainage and acidic soil. It features purplish-brown flowers in the spring and requires cross-pollination, so at least two and preferably three different varieties should be grown, but don’t plant them more than 30 feet apart. The tree produces an edible, sweet-tasting fruit later in the summer and into fall that is popular with people and ambitious wildlife. Wear gloves during harvest because contact dermatitis is known to occur. Suited for USDA Hardiness Zones 5-9, the Pawpaw grows well in naturalized, riparian or woodland areas. This flowering tree attracts butterflies, pollinators, small mammals and songbirds.


More detailed information about each of the 2024 Oklahoma Proven selections is available on the website. 

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