Kauai White torenia in the shade garden at the AgCenter Hammond Research Station in October 2013. (Photo by Allen Owings)

Downy mildew causes white fungal mycelium on the underside of impatiens leaves. This disease has become more prevalent in Louisiana the past couple of year. (Photo by Allen Owings)

Kauai Rose torenia. (Photo courtesy Ball Horticulture)

News Release Distributed 04/04/14

By Allen Owings
LSU AgCenter horticulturist

HAMMOND, La. – In the continuing program of identifying Louisiana Super Plants, the LSU AgCenter has identified the Kauai series torenia as a Louisiana Super Plant for spring 2014. These are improved from some of the older seeded varieties and have been proven great in landscape trials the last three years at the LSU AgCenter.

And as we move into the spring bedding plant season, torenias should be considered as prime candidates for our landscapes. It’s a good choice for a few warm-season flowers in the shady areas around your landscape, especially because most of our warm-season flowers prefer full sun or at least more sun than shade.

You can choose among many great bedding plants to provide desirable flowering and foliage for those shaded areas in your landscape through fall. In addition to torenia, you can find impatiens, begonias, caladiums and coleus among others.

Impatiens have traditionally been the top-selling warm-season flower for shade. Overall, it’s the most widely sold warm-season bedding plant around the country, and impatiens come in many flower colors. Although morning sun is fine, impatiens need shade from late morning through late afternoon, if possible, to perform best. Impatiens will flower throughout the warm season of the year.

For the past two years, a new problem has arisen with impatiens in the landscape. A new disease called impatiens downy mildew has devastated impatiens plantings statewide. This disease is a fungus and is extremely difficult to control. Due to this issue, growers, garden centers and landscapers are using fewer impatiens.

An alternative bedding plant to consider instead of impatiens is torenia, also called wishbone flower. Torenia is a great, underused shade-performing plant that more gardeners need to know. And one of the best of the torenia varieties is the Kauai series.

Kauai torenia flower colors include blue and white, lemon drop, deep blue, rose, burgundy and the unique magenta. You can also buy mixed colors of Kauai torenias. Most flowers have a yellow blotch on the flower petals.

These flowers are a native of Vietnam, so they are well-adapted to perform great in our hot and humid Louisiana climates. The recommended planting time is April through mid-May.

Torenias are considered a low-maintenance bedding plant. They’re short, mounding, compact growers, only reaching 8-10 inches tall and spreading 8-10 inches in the landscape. It is best to plant them 10-12 inches apart in a well-drained bed.

Plants bloom constantly from midspring through fall. And deadheading – removing old flowers – is not needed.

Kauai torenia will work well as companions to other plants most commonly planted with impatiens. Place torenias on the edges of plant beds, along the borders of shady or woodland gardens. They also work well in a shaded container along a pathway or on a patio where evening shade is provided.

Another torenia for Louisiana is the vegetatively propagated Summer Wave series. Flower colors include white, pink, purple, lavender and yellow. These are wider-spreading forms than what you will see with the Kauai series.

Warm-season bedding plants to consider that have been previously named Louisiana Super Plants are BabyWing begonias, Little Ruby alternanthera (Joseph’s coat), Butterfly pentas, Bandana lantanas, Senorita Rosalita cleome and Serena angelonias (summer snapdragon).

Louisiana Super Plants have a proven track record of several years of university evaluations combined with observations by industry professionals. Home gardeners and professional horticulturists alike can benefit from using Louisiana Super Plants, which are “university tested and industry approved.” You can see more Louisiana Super Plant information at www.lsuagcenter.com/superplants.

You can see more about work being done in landscape horticulture by visiting the LSU AgCenter Hammond Research Station website. Also, like us on Facebook. You can find an abundance of landscape information for both home gardeners and industry professionals at both sites.

Rick Bogren