Catharanthus roseus ~ Madagascar Periwinkle ~ Vinca Rosea ~ Rosy Periwinkle ~ Plant Care Guide

Common names:   

Madagascar Periwinkle, Rose Periwinkle, Periwinkle, Vinca, Old-Maid
Scientific name Catharantus roseus

Explanation of scientific name

Catharantus  – Greek for clean or pure flower
roseus            – Latin for rose-colored

Annual bedding plants seem to go in and out of fashion over the years.  Gardeners always yearn for something “new” or “different” and become bored with some species even though they perform well in the garden.  At one time petunias were the top selling annuals.  Today that distinction is held by impatiens.  While no one can tell what will be in vogue next, a contender might be the Madagascar Periwinkle.

By no means a new species, the Madagascar Periwinkle has been grown in this country since the 19^th century.  Many do not know it because of its many common names that are also applied to other species, causing confusion.  Even its scientific name, Catharantus roseus, causes problems since the species used to be known as Vinca rosea.

While the name may be perplexing, few question its beauty in the landscape.  Glossy, dark-green leaves on stems 3 – 18 inches tall (depending on cultivar) provide a perfect background for the single phlox-like flowers in shades of rose, pink, and white.  Blooms are produced continuously from June until frosts in the fall.  Madagascar Periwinkles thrive in full sun or partial shade.  They tolerate dry soils, but do poorly on wet sites.  The evenly moist soil of a typical annual garden suits them best.  Their tropical ancestry dictates a need for warmth, and experienced gardeners do not set them out too early in the spring.  Compared to other annuals, they are slow growing from seed and must be sown in February in order to have reasonably sized plants in May.  They can also be rooted from cuttings.  Essentially free of insects and diseases, even deer avoid them in favor of other annuals.

The renewed interest in Madagascar Periwinkle is the result of successes in plant breeding.  Hybridizers have been working with Madagascar Periwinkle for decades, with the cultivar ‘Polka Dot’, a dwarf trailing type, winning a prestigious All-American Selection Award in 1969.  Work at the University of Connecticut, crossing the Madagascar Periwinkle with its rare wild relatives produced an almost unheard of 3 All America Selection Award winners in 1991; ‘Pretty in Pink’, ‘Pretty in Rose’, and ‘Parasol’.  They have flowers several times larger than any previous type.  New cultivars are released regularly, increasing the popularity of the species.

The Madagascar Periwinkle’s value is not limited to ornamentation.  Its more important but often overlooked role is in medicine – with an interesting history.  While native to Madagascar and India, the species was transported throughout the tropics long before there was interest in the plant’s landscape potential.  It escaped cultivation and naturalized around the equator.  A diversity of cultures, from Madagascar to Jamaica to the Philippines, have a history of using it in folk medicines and especially for treating people with diabetes.  It is also known to be poisonous to livestock if ingested in large quantities.

The plant’s therapeutic uses came to the attention of Canadian and American medical researchers during World War II when they learned that soldiers stationed in the Philippines used Madagascar Periwinkle leaves to substitute for unavailable insulin.  During the 1950’s, while investigating the effects of Madagascar Periwinkle extracts, the researchers found them to have no appreciable effect on blood sugar levels, but they did reduce the white blood cell count in laboratory animals without significant side effects.  More recently, 2 alkaloids in Madagascar Periwinkle leaves, vinblastine and vincristine, were identified as active anti-cancer agents that could be used in chemotherapy.  Vinblastine is used for patients with Hodgkin’s disease and vincristine is used for children with leukemia.  With the introduction of vincristine, the survival rate for children with leukemia jumped from 20 to 80 percent.

The lesson of the usefulness of this single, once obscure species should not be lost.  Madagascar has an incredible number of unique plant and animal species that are becoming extinct at an astonishing rate, as the Malagasy people level natural vegetation to plant crops to feed an exploding population.  While one can be sympathetic to their immediate food needs, there are probably many plants with potential medical, industrial, food, or ornamental uses that will disappear before we learn of their value.  The tragedy of extinction is that each species is the product of millions of years of evolution that will never be duplicated.

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Common Name: vinca

Type: Herbaceous perennial
Family: Apocynaceae
Zone: 10 to 11
Native Range: Madagascar
Height: 0.5 to 1.5 feet
Spread: 0.5 to 1.5 feet
Bloom Time: June to To frost
Bloom Color: Pink, Red
Bloom Description: Rosy pink to red with mauve throats
Sun: Full sun to part shade
Water: Medium
Maintenance: Low
Flowers: Showy Flowers
Tolerates: Dry Soil, Drought, Rabbits
Uses: Suitable as Annual
Invasive: Where is this species invasive in the US?

Culture

Winter hardy to USDA Zones 10-11 where it grows as a woody based perennial. In the St. Louis area, it is best grown as an annual bedding plant in well-drained sandy loams in full sun to part shade. Needs regular moisture, but avoid overhead watering. Superior soil drainage is the key to growing this annual well. Start seeds indoors 12-16 weeks before last frost date. Set out seedlings or purchased starter plants in spring after last frost date. Thrives in hot and humid summer weather. Cuttings may be taken from plants in late summer for overwintering so as to provide a stock the following spring. Container plants may be overwintered indoors. May self-seed in optimum growing conditions.

Noteworthy Characteristics

Periwinkle, Madagascar periwinkle or annual vinca is an erect to spreading tender perennial in the dogbane family typically mounding 6-18” (less frequently to 24”) tall and as wide. It produces attractive bushy foliage that is covered by an often profuse bloom of phlox-like flowers from summer to frost. Best flowering is in summer. Tubular flowers have five flattened petal-like lobes and appear singly in the upper leaf axils. Species flowers are rosy-pink to red with mauve throats. However, species plants are seldom seen in commerce today, having been largely replaced by larger flowered cultivars, many of which are dwarf to compact plants that sometimes have overlapping petals. Cultivars expand the available color range to include pale pink, rose, hot pink, red, lilac, and white, often with contrasting darker throats/eyes. Oblong to ovate glossy green leaves (to 2” long). Synonymous with and formerly know as Vinca rosea.

Problems

No serious insect or disease problems. Stem rot, leaf spot and aster yellows may occur. Watch for slugs and snails.

Garden Uses

Annual ground cover, bedding, edging or containers. Some varieties make excellent houseplants.

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See Also ….

Anti-cancer: Rosy periwinkle

Vinca, Madagascar Periwinkle

MADAGASCAR PERIWINKLE

Catharanthus roseus (Madagascar periwinkle)