By Ralph E. Mitchell
While periwinkles (aka vinca) are known for taking hot summers, they often don’t do well with too much moisture and resulting disease susceptibility. As a result, they often succumb to various foliar and root rot fungal problems. The beautiful green foliage and flowers can brown and turn into mush in as little as two-weeks. However, for every plant problem, there is an opportunity and commercial research by a seed company paid off with a disease-resistant periwinkle named Cora™ . Say hello to Cora™ if you like periwinkles!
Specifically, Cora™ is resistant to the aerial Phytophthora fungus. You may also see Nirvana™ brand periwinkles. These are just the same, but are vegetatively produced instead of started from seed. Cora™ is not only disease-resistant, but also more attractive ! The leaves and the flowers of this series are larger and the foliage is glossy and deep green. The colors come in a wide assortment including white, lavender, deep lavender, apricot with a red center, pink, burgundy and violet. In general, periwinkles are very carefree and do best in soils relatively average in nutrients. They need well-drained soil which does not contain much organic matter. This sounds like our typical residential fill soil which will do very nicely. Water to establish the plants, and then keep any irrigation to a minimum to help ward off root rots. Plant individual plants in full sun at the same depth that they were in the container – no deeper. If all goes well, expect each plant to spread up to two-feet wide with a height of about sixteen inches. Cora™ periwinkles make great summer plants for bedding, for use in containers, and in hanging baskets.
While periwinkles are perennial plants, they will tend to get a bit woody and less attractive as they age and fall victim to frosts and/or wear and tear. Now while Cora™ (and Nirvana™) is resistant to a certain aerial fungus, it can still contract certain root-rotting fungal organisms, so be careful not to over-water.
This periwinkle is generally available as ready-to-install plants from local garden centers, and from seed via your favorite gardening catalog. I am trying some Cora™ periwinkles this year. Say hello to Cora™ this summer! For more information on all types of bedding plants suitable for summer planting, please call our Master Gardener volunteers on the Plant Lifeline on Mondays, Wednesdays and Fridays from 1 to 4 pm at 764-4340 for gardening help and insight into their role as an Extension volunteer. Don’t forget to visit our other County Plant Clinics in the area. Please check this link for a complete list of site locations, dates and times – http://charlotte.ifas.ufl.edu/horticulture/Plant%20Clinics%20Schedule.pdf.
Caldwell, D. ( 2008) A Rainey Season Periwinkle? The University of Florida Extension Services, IFAS – Collier County.
Pemberton, B. (2017) Vinca Cora Series. Texas Superstar® program, of Texas AgriLife Research, Texas A&M University.
(2017) UF/IFAS Gardening Solutions. Periwinkles. The University of Florida Extension Service, IFAS.