Q: What are the big white flowers I see in roadside ditches?
A: There are many showy, native plants along roadside ditches. A summer bloomer often grown in gardens is aptly named swamp mallow, Hibiscus moscheutos. It’s a hardy herbaceous hibiscus that makes an attractive shrub growing 4- to 6-feet tall with fuzzy foliage crowned by 6- to 8-inch white blossoms with maroon centers. There are many similar hibiscus shrubs native to Texas and the southeast U.S. The scarlet rosemallow, or Texas Star, has stunning distinct red petals and also comes in a white version, both with star-shaped leaves. Mercer Botanic Gardens has a fence-line row of these floral giants, many of which were hybridized by plant breeder Dr. Ying Doon Moy. The most popular variety available in nurseries is called Moy Grande, which features a play on his name and was developed at the San Antonio Botanical Garden. Moy also produced other beauties at Mercer with various shades of red, rosy pink, and white flowers that measure 10- to 12-inches across. These are a rare treat to see while driving by the Mercer gardens!
To bring a tropical look to gardens, these plants put on dramatic growth each spring and display glorious blooms in the sun and heat of summer. After they set seed, the stems die back during frosts. Cut back dead stems to a few inches in height, and when the ground warms, they will regrow and bloom for years of enjoyment.