Oklahoma Proven plants can help gardeners succeed

Wednesday, March 11, 2015

When it comes to gardening in what can be some pretty harsh environmental conditions in Oklahoma, gardening enthusiasts may need a leg up when it comes to selecting plants, shrubs and trees for their landscapes.

Fortunately for these gardeners, much research has gone into selecting plants that have proven themselves to be worthy of being named as Oklahoma Proven Plant Selections.

David Hillock, Oklahoma State University Cooperative Extension consumer horticulturist, oversees the Oklahoma Proven Plant Selection program and said the 2015 selections have just been announced.

“Every year a set of plants is chosen by horticulturists that have been proven to do well in Oklahoma’s diverse climate and growing conditions,” Hillock said. “Oklahoma Proven began in 1999 and has been providing gardeners with wonderful plant selections for 17 years. The program began by selecting a tree, shrub, perennial and annual, and in 2009 added a new category called Collector’s Choice.”

The Collector’s Choice selection is for the adventuresome gardener and has been shown to do well in Oklahoma, but it may require special placement or a little extra care.

The 2015 Oklahoma Proven selections promise to provide gardeners with a lot of color and texture to highlight the landscape. This year’s tree selection is the hedge maple, the shrub is the barberry (columnar forms), the perennial is the Summer Phlox Volcano^® series and the annual is the spider flower. The Collector’s Choice selection is the black gum.

Black gum, also known as black tupelo or sour gum, is an eastern native. Black gums generally are slow to moderate growers, reaching a height of 50 feet to 60 feet or more. They make excellent shade trees with beautiful summer foliate and brilliant fall color. They grow well in full sun to part shade and prefer moist, well-drained soil. Improved varieties of black gums should be considered as they offer better form, brilliant fall colors and better disease resistance. One selection, ‘Wildfire,’ even offers red shoots on new growth.

The hedge maple is a small to medium sized tree growing to 25 feet to 35 feet high and wide. Its compact size makes it a great selection for smaller, urban landscapes, and even under utility lines. In the summer its foliage is a beautiful green, and in the fall the leaves turn a yellow to yellow-green color.

“The branches often develop very low to the ground, which allows the hedge maple to provide excellent coverage for wildlife, but it also can easily be limbed up,” Hillock said.

Barberries are a fairly tough shrub and offer a wide variety of leaf color. The newest varieties are the columnar types that offer a vertical element in the landscape. Depending on the cultivar, plants grow 3 feet to 5 feet high and not more than 2 feet wide. While they prefer moist, well-drained soils, they are adaptable to a wide range of soils. Once established the barberry can be quite drought tolerant.

Plants of the Volcano^® series are more compact, more floriferous and more powdery mildew tolerant than other varieties of summer phlox. The flowers are larger, fragrant and borne in abundance on sturdy stems with deep green leaves and grow to be 24 inches to 28 inches tall. The Volcano^® series flower colors range from red, pink, ruby, white, lavender and purple. The flowers also may have eyes of pink, red or white or may be bicolored. While they grow best in full sun, they will grow in shady areas.

“Keep in mind that too much shade and poor air circulation will increase chances of mildew developing,” he said. “This plant can be grown as an accent or in larger group plantings. As an added bonus, butterflies and hummingbirds are attracted to the colorful, fragrant flowers.”

The final Oklahoma Proven selection this year is the spider flower. The flowers have abnormally long stamens that give the flowers a frilly look, which resembles spider legs. Flower colors come in shades of white, pink, blue and purple. The plants grow 3 feet to 6 feet tall, depending on the cultivar, and do well in full sun to part shade with well-drained soils. Improved varieties of spider flower are stockier, bushier and bloom longer than older types.

“While there’s never a guarantee in gardening, gardening enthusiasts who use the Oklahoma Proven selections definitely are a step ahead of the game when it comes to a successful garden,” Hillock said. “Oklahoma has very diverse growing conditions when it comes to soil, moisture and heat. Making selections that have proven themselves to do well in such diversity definitely puts Oklahoma gardeners at the head of the pack. Be sure to look for the Oklahoma Proven signs and posters at your local nursery.”

Gardening enthusiasts who wish to see full color photos of the 2015 Oklahoma Proven selections can go to http://www.oklahomaproven.org. Oklahoma Proven is sponsored by the OSU Cooperative Extension Service; OSU Department of Horticulture and Landscape Architecture; Oklahoma Department of Agriculture, Food and Forestry; US Department of Agriculture Forest Service; The Botanic Garden at OSU; Oklahoma Nursery and Landscape Association; and Horticulture Technologies at OSU/OKC.