Gardeners' Dirt: Vincas provide color for summer
By Linda Hartman - Victoria County Master Gardener Edited by Charla Borchers Leon
Aug. 2, 2012 at 3:02 a.m.
They are everywhere. Just about every place you look. No, not the kids who are enjoying their summer break, but the colorful vinca plants. One can find them in flowerbeds, in containers, on street corners and in public parks.
The question is, "Which vinca? Vincas major or vinca minor or vinca flower?"
The name "vinca" can be a bit confusing. The vinca major is known as the annual vinca vine, which has variegated leaves and prefers well-drained soil and partial shade.
Vinca minor is a shade-loving perennial ground cover with its blue flowers appearing in the spring.
These two plants can be used in containers or as ground cover.
The vinca flower is known as Catharanthus roseus. As an annual flowering plant, it is deer-resistant, drought-tolerant, maintenance-free and equally at home in the garden or in containers.
The summer flowering vinca has undergone a few name changes, but the modern cultivars are the results of hybrids made between Catharanthus roseus and other Catharanthus species. It is also identified as the Madagascar periwinkle.
Vincas, a.k.a. periwinkles
Vincas or periwinkles (both names are correct) are hot weather annuals found in all growing areas. They grow from 8- to 18- inches tall while spreading up to 2 feet. These colorful plants thrive in full sun, and are considered to be free-flowering, self-cleaning plants with no deadheading necessary. Vincas like to be fertilized every two weeks.
The best soil for vincas is a well-drained, slightly acidic soil with a pH of 6 to 6.5. It does not need a rich or fertile soil. Perhaps this is the reason we are seeing vincas everywhere.
Bad news, good news
• Susceptible to fungus
Vincas are susceptible to aerial phytophthora, which is a fungus found in the soil. Texas has the nicotianae fungus, which will cause the stems to turn black and the death of the plant. If found in your garden, remove the dead plants and discard in the garbage.
In 2007, Brent Pemberton, Texas AgriLife research horticulturist, found a disease-resistant vinca.
Jerry Parsons, Texas AgriLife Extension Service horticulturist in San Antonio, was quite skeptical stating that no vinca would live a month in his area.
Pemberton worked with Ryan O'Callaghan, of Goldsmith Seed; Larry Barnes, of Texas A&M University; Darrell Thomas, of Goldsmith Seed; Forrest Appleton, of Hollywood Park; and Mark Sequin, of Fischer Plants, to research and field test the Nirvana vinca.
Awarded Superstar status
Numerous areas in Texas were chosen as test sites, and in 2009, the Nivrana and Cora series were awarded the status as Texas Superstars.
The Texas Superstar designation is awarded by Texas AgriLife horticulture specialists and researchers based on the plant's performance under the toughest conditions with only the most hardy and most stunning plants making this list. Observations and data from replicated trials across the state are used to determine which plants are deemed Texas Superstars.For reference information on Superstars, go to plantanswers.com or texassuperstar.com.
• Almost carefree
Periwinkles have been seen throughout communities in numerous plantings because they are almost carefree and work well in hot and dry conditions while providing prolific color.
Typically planted in early summer, they can still be added to landscape beds or containers and flourish with very little care once rooted in.
Remember to space plants 8 to 10 inches apart in beds to encourage plant strength. Water with a soluble fertilizer for a couple of weeks, and then give them an infrequent drink when dry. Avoid the use of overhead sprinklers to prevent fungus.
No wonder they qualify for Superstar status and are everywhere with such little care required.
Available in many colors
Thirty years ago, colors were limited to white with a red eye. Breeders crossed the Catharanthus roseus with other species to improve color range, flower size, and growth size. Periwinkles are now available in pink, red, deep rose, lavender blue, peach apricot and many other shades. Combinations of these will create an eye-catching addition to any garden. Enjoy the beauty - they are everywhere.
The Gardeners' Dirt is written by members of the Victoria County Master Gardener Association, an educational outreach of Texas AgriLife Extension - Victoria County. Mail your questions in care of the Advocate, P.O. Box 1518, Victoria, TX 77901; or firstname.lastname@example.org, or comment on this column at VictoriaAdvocate.com.