News Release Distributed 07/09/10

By LSU AgCenter horticulturists Dan Gill, Kyle Huffstickler and Allen Owings

One of the most popular summer bedding plants in Louisiana is vinca, also called periwinkle. This annual plant is known for having a very long blooming season. It is also very heat- and drought-tolerant.

The vinca or periwinkle we use as a bedding plant is Catharanthus roseus. Great improvements have been made in vinca flower colors over the past 15 years. In addition, many new series and varieties of these popular plants have debuted. Vinca flower colors now include pink, deep rose, red, blush, scarlet, white, white with a red eye, lavender blue, peach, apricot, orchid, burgundy and many other shades.

Vinca generally grow from 10 to 18 inches tall with a spread of about 1 foot, although trailing types spread to about 2 feet.

We do have a problem with vinca in landscape plantings some years. The culprit is a fungus called Phytophthora, and it has always been present in our soils. It is often responsible for root rots and crown rots, and it attacks many types of plants. Rhizoctonia is another disease common on vinca in Louisiana. To avoid disease problems on your vinca, consider the following LSU AgCenter recommendations:

– Select a full-sun location. Vinca need at least six to eight hours of direct sun daily for optimum performance.

– Properly prepare the landscape bed to allow for drainage and aeration. Raise the bed at least 6 inches if drainage is questionable.

– Avoid planting vinca too early. Late April through early May is the ideal first planting date for the spring. You can continue planting vinca throughout the summer.

– Plant so that the top of the root ball is level with or slightly higher than the soil of the bed. Proper spacing also is important because a crowded planting limits air circulation and can create conditions more favorable to disease development. Space transplants at least 8 inches apart.

– Mulch to decrease splashing of rainfall and irrigation water from soil to the lower stems and foliage of the plants. Bedding plants should be mulched to a depth of about 1 inch. Pine straw is the preferred mulch material.

– Manage irrigation properly. Vinca need very little irrigation once they’re established. Avoid overhead irrigation.

– Don’t plant vinca in the same bed year after year. Rotate them with other summer bedding plants that like sunny locations such as blue daze, dwarf lantana, dwarf pentas, scaevola, verbena, melampodium or sun-tolerant coleus, to name a few.

Some of the varieties of vinca available include Pacifica, Cooler and Mediterranean. The Victory series has been introduced in the past 10 years and has performed well in Louisiana and Texas trials. The newest vinca are the Titan, Nirvana and Cora series. These all have been very good performers in LSU AgCenter trials at the Hammond Research Station in Hammond and at Burden Center in Baton Rouge. The Titans have the largest flowers of all the vinca groups, while Nirvana and Cora vinca have genetic resistance to Phytophthora.

Two vinca series we have not grown before are in our AgCenter trials this year.

Vinca can have trouble through the summer and fall months if proper cultural practices are not followed, so consider the above options to improve your success.

Visit LaHouse in Baton Rouge to see sustainable landscape practices in action. The home and landscape resource center is near the intersection of Burbank Drive and Nicholson Drive (Louisiana Highway 30) in Baton Rouge, across the street from the LSU baseball stadium. For more information, go to www.louisianahouse.org and www.lsuagcenter.com/lyn.