When selecting flowering annuals this spring, don't forget annual vinca (Catharanthus roseus). Annual vinca, also known as Madagascar periwinkle, is the perfect plant for sunny garden areas. In addition to being a wonderful plant for beds and borders, annual vinca can also be grown in containers, window boxes, and hanging baskets.

Annual vinca commonly grows 8 to 12 inches tall, but some varieties can reach a height of 18 inches. Plant spread is typically 12 to 18 inches. Annual vinca produces 1- to 2-inch-diameter flowers above glossy, dark green foliage. Until recent years, the range of flower colors was somewhat limited. Flowers varied from pink to white, often with dark rose or red eyes. Over the past few years, seed companies have developed a large number of new varieties. These new varieties have expanded the color range of annual vinca. Gardeners can select varieties with light blue, pink, salmon, apricot, orchid, raspberry, carmine, and burgundy flowers. Plant breeders have also introduced varieties with trailing and dwarf, upright growth habits.

Annual vinca is easy to grow. It performs best in well-drained soils in sites that receive partial to full sun. Annual vinca possesses excellent heat and drought tolerance, blooming continuously through the intense heat of mid-summer. However, Madagascar periwinkle does not perform well in wet, poorly drained soils or in cool spring weather. Plants turn a sickly yellow green in wet soils or cool spring weather. When choosing a planting site, make sure it has well-drained soil. Also, allow the temperatures to warm nicely before planting in the spring. Annual vinca is free of serious insect and disease pests.

Annual vinca is a low maintenance, relatively trouble-free bedding plant. It blooms from spring until a killing frost in the fall. The removal of faded flowers or deadheading is not necessary. While root and stem rots may occur, these problems can usually be avoided by planting in warm, well-drained soils.

Cultivars and series of annual vinca include:

(Varieties within a series possess uniform characteristics, such as height, spread, and flowering habit. The only characteristic which varies within a series is flower color.)

Annual vinca should not be confused with perennial periwinkle (Vinca minor), which is also known as common periwinkle, myrtle, and running myrtle. This species is a viney broadleaf evergreen and is commonly used as a groundcover in partial shade. Common periwinkle grows 3-6 inches tall and spreads over 2 feet. It has smooth wiry stems and lilac-blue flowers.

Common periwinkle, like annual vinca, is easy to grow. It grows best in well-drained organic soils with a pH between 6.0 and 8.0. Vinca minor flowers best in full sun. However, its leaves may burn in sunny locations.

Cultivars of common periwinkle include:

Both annual vinca and common periwinkle are easy-to-grow species that are wonderful additions to the home landscape.

This article originally appeared in the May 4, 2001 issue, pp. 50-51.