These plants earn their places in thriving Oklahoma gardens and landscapes. They've been tested and approved by local horticultural experts.
Each spring, the Oklahoma Proven Selections program announces four additions to its plant selections: one tree, one shrub, one perennial, and one annual. These Proven Selections have been tested across the state for their ability to thrive in Oklahoma gardens and landscapes. To earn the designation, plants must show good pest and disease resistance, provide more than one season of interest, and require a low level of maintenance.
Korean spice viburnum (Viburnum carlesii)
Korean spice viburnum is an easy-to-grow shrub with three-season appeal. In late spring, clusters of pink buds open into white flowers with a pink blush. The flowers are beautiful, but the spicy fragrance will knock you off your feet. The dark green foliage always looks neat and tidy on this 4- to 5-foot-tall shrub. In late summer, red berries turn to black and stand out nicely against the wine-red fall color. It prefers moist, well-drained soil in full sun to part shade. Zones 5-7
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'Valley Forge' American elm (Ulmus americana 'Valley Forge')
At one time landscapes were home to many majestic elm trees. Sadly, Dutch elm disease devastated the population. Now new and improved, disease-resistant elms are on the market. Of all the new varieties, 'Valley Forge' has been shown to be the most disease-resistant. It has a broad V-shape form, eventually reaching 60 feet tall. It has yellow fall color. American elms are adaptable to a wide variety of soil conditions; they tolerate deicing salts, air pollution, and drought once they are established. Zones 3-9
Red chokeberry (Aronia arbutifolia)
This 6- to 10-foot-tall native shrub has something for everyone. Clusters of white to light pink flowers bloom in spring, providing nectar for hummingbirds and butterflies. Clusters of glossy red fruit replace the blossoms in autumn. The fruit persists into winter, extending the season of interest because birds don't like them until they've frozen a few times. Bright red fall color makes red chokeberry a terrific alterative to the non-native burning bush. Chokeberry prefers average soil in full sun or part shade. Zones 4-9
Giant coneflower (Rudbeckia maxima)
Native to Oklahoma, giant coneflower is a powerhouse of summer color. The stems can reach 5-6 feet tall, so give this perennial a place in the back of a border or plant it in a meadow for a strong vertical accent. The lovely flowers -- with bright golden ray petals that surround a dark brown cone -- draw butterflies, which you'll see at eye level thanks to the tall stems. Finches clamor to get to the seeds in the cones in late summer. The powdery blue stems and foliage don't need staking. Giant coneflower blooms in summer and looks best planted in drifts. It prefers moist, well-drained soil in full sun but tolerates light shade. Zones 4-8
Persian ironwood (Parrotia persica)
"One of the best small specimen trees that I know," says Michael Dirr, author, educator, and guru of woody plants. That is high praise, and it's true that few small trees can rival this Persian beauty, which grows 20-40 feet tall. It flowers very early in spring, before the foliage unfurls, with red-and-white blooms. The flowers aren't large, but they're quite pretty upon inspection. The new foliage is reddish purple, changing to glossy green for the summer, and ending the season in a combination of yellow, orange, and scarlet. Interesting bark adds to the winter landscape. Grow the tree in full sun or part shade. Zones 5-8
Diabolo ninebark (Physocarpus opulifolius 'Monlo')
This selection of native ninebark has deep purple, nearly black foliage, making it a showstopper in the landscape. In late spring, little bunches of pinkish-white flowers bloom all the way down the arching branches and really stand out against the dark foliage. The flowers give way to small purple fruits. The foliage may become a touch greener in warm climates. The shrub grows 4-8 feet tall and tolerates a range of soil conditions. In Oklahoma, it's happy for some shade from the hot afternoon sun. Unique bark adds interest to the winter garden. Zones 2-7
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Bosnian pine (Pinus heldreichii )
As the name suggests, this hardy pine is native to southeastern Europe. It is a slow-growing evergreen with an upright, pyramid-shape form. The branching is somewhat open, so it looks nice planted with more tightly branched yews and spruces, adding diversity to an evergreen planting. The tree grows 20-30 feet tall -- not a giant in the world of pines -- making it a great choice for suburban gardens. It prefers full sun and average garden soil. This pine is quite drought-tolerant once established. It's sometimes called Pinus leucotomies. Zones 5-6
Shantung maple (Acer truncatum)
Shangtung maple is an underappreciated, small shade tree, just perfect for Oklahoma gardens. It grows 25-30 feet tall. New foliage emerges with a reddish tint, quickly changing to deep green. In the fall, the tree turns attractive shades of yellow, orange, purple, and red. It is quite versatile and can tolerate wet or dry situations, along with drying winds, better than most other maples. Once established, the tree has good drought tolerance. Zones 4-8
'Magnus' purple coneflower (Echinacea purpurea "Magnus')
'Magnus' has become a much-loved staple in gardens. It has strong 2.5- to 3-foot-tall stems to hold up deep purple-pink flowers and does not need to be staked. The center cones are orange, turning brown when mature. The flowers are often used in fresh and dried arrangements, and small birds love the seeds inside. Butterflies rush to the blossoms for nectar. Purple coneflower looks lovely combined with Russian sage and blazing star. Grow it in full sun and well-drained soil. Zones 3-8
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Winter jasmine (Jasminum nudiflorum)
It's so exciting to have plants that bloom in the winter. It's like getting a bonus! Winter jasmine blooms with bright yellow flowers in late winter before the leaves unfurl. It can be grown as a climber on a trellis, where it will reach 12-15 feet tall. Or it can be left to become a groundcover that will reach about 4 feet tall. Winter jasmine also looks pretty falling over a wall. Plant it on the south side of the house, where it will get good winter light and produce the most flowers. It's best grown in well-drained, sandy loams with regular moisture. Zones 6-10
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Japanese painted fern (Athyrium nipponicum pictum)
This fern was chosen as the Perennial Plant of the Year in 2004. It has incredible metallic silver-gray foliage colored with hints of red and blue. It provides charming contrast to more subtle shade plants. Japanese painted fern grow 12-18 inches tall and is extremely low-maintenance. It combines well with hosta, foamflower, sedge, and astilbe. The pretty fronds are lovely in flower arrangements. The fern prefers part to full shade and moist, humus-rich soil. Zones 4-8
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Silver linden (Tilia tomentosa)
Silver linden, or lime tree as it is sometimes called, is a beautifully shaped shade tree. It eventually reaches 50-70 feet tall and 25-35 feet wide, with a broad columnar to pyramidal shape. The foliage is glossy dark green on top and slivery beneath. When even the slightest breeze blows through the leaves, the silver is revealed, and the tree seems to shimmer. In midsummer, the extremely fragrant soft-yellow flowers bloom, enveloping the whole tree and attracting butterflies. Silver linden is tolerant of pollution in urban settings. It prefers moist, well-drained alkaline soil and full sun. Zones 4-11
Bald cypress (Taxodium distichum)
This tall, majestic tree has some very unusual traits. It looks like an evergreen tree with feathery green needles, but around Thanksgiving the needles turn coppery-orange and fall to the ground. You may come across this tree in a swamp, standing in water with roots called knees, which grow above the surface for air. This regal-looking tree will reach a grand height of 50-70 feet tall and grow about half as wide. Bald cypress likes acidic soil and full sun. Zones 4-11
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Arizona cypress (Cupressus arizonica)
Arizona cypress is a native tree that is sometimes used as a Christmas tree. The soft-texture gray-green needles look braided. The shredding gray-brown bark of older trees is also ornamental. Featuring a pyramidal shape, Arizona cypress is a fast-growing tree, reaching 20-30 feet tall and 15 feet wide. It is drought-tolerant once established and can stand up to harsh winds. The tree makes a nice evergreen accent plant. It's also great for windbreaks and erosion control. Zones 7-9
Lenten rose (Helleborus)
Plants that flower in the winter offer hope that spring is on its way. Lenten rose got its name because it flowers in late winter, about the time the Lenten season begins. The roselike flowers range in color from white to rose-purple, no two being exactly alike. The perennial grows 1-2 feet tall. Plant Lenten rose in groups, and the dark green foliage will make a fine groundcover the rest of the year. It appreciates a spot sheltered from cold winter winds. The deer-resistant Lenten rose is best grown in rich, well-drained soil in partial or full shade. Zones (4) 5-9
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