Looking for another gorgeous and interesting ornamental plant to have around? Madagascar Periwinkle is waiting for you to bring it home and it has a lot to offer! Its lovely appearance makes it just perfect as bedding and border plant, ground cover, or even potted in eye-catching containers or hanging baskets. Read on to find out more about this low-maintenance plant.
I. Appearance and CharacteristicsÂ
Catharanthus roseus, commonly known as bright eyes, Cape periwinkle, graveyard plant, Madagascar periwinkle, old maid, pink periwinkle, rose periwinkle, is a perennial species of flowering plant in the family Apocynaceae. It is native and endemic to Madagascar, but is grown elsewhere as an ornamental and medicinal plant, and now has a pantropical distribution. It is a source of the drugs vincristine and vinblastine, used to treat cancer. It was formerly included in the genus Vinca as Vinca rosea.
It has many vernacular names among which are arivotaombelona or rivotambelona, tonga, tongatse or trongatse, tsimatiririnina, and vonenina.
Catharanthus roseus is an evergreen subshrub or herbaceous plant growing 1 m (39 in) tall. The leaves are oval to oblong, 2.5–9 cm (1.0–3.5 in) long and 1–3.5 cm (0.4–1.4 in) wide, glossy green, hairless, with a pale midrib and a short petiole 1–1.8 cm (0.4–0.7 in) long; they are arranged in opposite pairs. The flowers range from white with a yellow or red center to dark pink with a darker red center, with a basal tube 2.5–3 cm (1.0–1.2 in) long and a corolla 2–5 cm (0.8–2.0 in) diameter with five petal-like lobes. The fruit is a pair of follicles 2–4 cm (0.8–1.6 in) long and 3 mm (0.1 in) wide.
In its natural range along the dry coasts of southern Madagascar, Catharanthus roseus is considered weedy and invasive, often self-seeding prolifically in disturbed areas along roadsides and in fallow fields. It is also, however, widely cultivated and is naturalized in subtropical and tropical areas of the world such as Australia, Bangladesh, India, Malaysia, Pakistan, and the United States. It is so well adapted to growth in Australia that it is listed as a noxious weed in Western Australia and the Australian Capital Territory, and also in parts of eastern Queensland.
II. How to Grow and Care
Sunlight
Madagascar periwinkle thrives in ample sunlight, but in the intense heat of the summer, especially around the highs of noon, the madagascar periwinkle should not be exposed to direct sunlight. Instead, keep it partially shaded, but allow it to receive full sunlight the rest of the time, so that it blooms continuously with large and colorful flowers.
Temperature
Madagascar periwinkle likes a warm and moist environment. Since it is not resistant to drought, it needs to be regularly watered during hot and dry seasons.
In terms of temperature requirements, this varies with the seasons; in the spring and summer, an ideal temperature would be around 18 to 25 ℃, although it is also resistant to a high of around 30 ℃. In the winter, the temperature can drop to between 13 to 18 ℃. Due to its poor hardiness, the minimum temperature should never be lower than 5 ℃.
Watering
Watering too frequently is a common mistake with annual vinca. Water when the top inch of soil feels dry to the touch. Moderate weekly watering is ideal, but do not water at all if your garden is getting regular rainfall. This is a plant that thrives in dry soil.
Soil
As a tropical plant, the madagascar periwinkle likes slightly acidic soil, meaning that alkaline soil should be avoided. If its soil is too alkaline, its roots will grow poorly and its leaves tend to turn yellow, causing the plant to grow thin and weak. In severe cases, the plant won’t be able to bloom, and could even die. Ideally, use loose, permeable, and well-drained loam for planting. Peat, along with organic fertilizer, can be added to improve soil fertility.
Fertilizing
Application of a base fertilizer before planting: madagascar periwinkle likes loose and fertile soil, so it is best to add a certain amount of base fertilizer before planting, such as an organic fertilizer. A base fertilizer will increase the nutrients in the soil and ensure good growth in later stages.
Fertilization during the growth period: The madagascar periwinkle needs a large amount of fertilizer during its growth period, benefiting from an application once a fortnight. A compound fertilizer and a high-nitrogen foliar fertilizer can be applied alternately. However, take care not to excessively fertilize, as this can damage the plant.
Fertilization during the propagation period: Before and during blooming, the madagascar periwinkle consumes a large amount of nutrients, meaning that sufficient fertilizer should be provided in order to ensure a large number of flowers and a prolonged blooming time. An organic fertilizer with a high phosphorus and potassium content is most commonly used, along with a compound fertilizer to supplement this. Topdressing should be carried out once a month. Your fertilizer concentration should not be too high, otherwise the plant will not be able to properly absorb it. Correct fertilizer amounts will give you better-looking flowers, improving the plant’s ornamental value.
Planting Instructions
Spring is the normal sowing time for the madagascar periwinkle. For early blooming, sowing can be done in early spring in a greenhouse, with the temperature being maintained at around 25 ℃. Once the temperatures warm up later in the spring, plants can be moved to an outdoor space. It is best to prepare the soil for sowing with peat and perlite at a proportion of 3:1, and leaf mold can also be applied. A fungicide can be used if you need to ensure that the soil is fully sterile, and the container can then be placed in a sunny location.
Note that the seeds should not be exposed to light; water them sufficiently and then cover with a film to keep the soil moist. Seedlings usually emerge in 7-10 days. After seedling emergence, weak seedlings should be removed, leaving only the strong seedlings to grow. This will ensure adequate air ventilation between seedlings, as well as sufficient sunlight. Young plants can be sprayed with a fungicide once a week for 2-3 weeks in succession to prevent damping off. After that, they can be transplanted.
Pruning
Madagascar periwinkle should be pruned once from the seedling stage to the blooming period, with the main pruning method being pinching. Once 4-5 leaves grow out from a seedling, the terminal bud should be pinched. The terminal buds of lateral branches should be pinched after 4-5 leaves grow out from each lateral branch. Repeat the pinching process 4-5 times to encourage fuller and plumper growth.
The madagascar periwinkle has a large number of flowers, but is prone to dying after blooming, or simply refuses to bloom again. To prevent this, the withered flowers should be cut off in time, which will allow the lateral branches to bloom again.
Propagation
Madagascar periwinkle can be propagated by sowing or cuttings.
The best time for cuttings is generally in the summer, when the temperature and humidity are higher, which is favorable for rooting. Before taking a cutting, the culture medium needs to be prepared with peat, perlite and vermiculite, at a proportion of 4:1:1, and should be sufficiently watered once. Cut a 10 to 12 cm long branch, and keep just 1-2 leaves at the top. Make sure that you use scissors rather than hands, so as to avoid infection.
plant cuttings deep into their growing medium, spraying with water and then covering with a plastic bag. Keep it at a temperature of around 20 to 25 ℃, with the humidity at around 60%. It should take root in about 20 days.
Pests and Diseases
Brown Spot on Leaves
Annual, vinca can succumb to numerous fungal diseases, like leaf spot, botrytis blight, even root rot. These kinds of problems happen because of dampness, and lack of airflow. This problem is easily fixed by thinning out the plants—trim away all affected leaves with a clean, sharp garden shear—and applying a fungicide.
Yellow, Wilted Leaves
If your annual vinca’s leaves are yellowing and wilted, it’s likely your plant is getting too much water. Stick your finger into the soil: Is it soaked? Yellowing, wilted leaves are a sign of too much moisture, which is easy to remedy.
III. Uses and BenefitsÂ
- Traditional uses
The species has long been cultivated for herbal medicine, as it can be traced back to 2600 BC Mesopotamia. In Ayurveda (Indian traditional medicine) the extracts of its roots and shoots, although poisonous, are used against several diseases. In traditional Chinese medicine, extracts from it have been used against numerous diseases, including diabetes, malaria, and Hodgkin’s lymphoma. In the 1950s, vinca alkaloids, including vinblastine and vincristine, were isolated from Catharanthus roseus while screening for anti-diabetic drugs. This chance discovery led to increased research into the chemotherapeutic effects of vinblastine and vincristine. Conflict between historical indigenous use, and patent from 2001 on C. roseus-derived drugs by western pharmaceutical companies, without compensation, has led to accusations of biopiracy.
- Ornamental uses
Madagascar periwinkle is an evergreen herbaceous perennial commonly found in gardens within warm climates. It is prized for its colorful and vibrant blooms in the summer months. The pretty flowers mean that it is grown as an ornamental with its trailing stems making it suitable for ground cover. Madagascar periwinkle is appropriate for rockeries and roadsides. Plant with other periwinkles or ferns for strong color contrasts.
- Medicinal uses
Vinblastine and vincristine, chemotherapy medications used to treat several types of cancers, are found in the plant and are biosynthesised from the coupling of the alkaloids catharanthine and vindoline. The newer semi-synthetic chemotherapeutic agent vinorelbine, used in the treatment of non-small-cell lung cancer, can be prepared either from vindoline and catharanthine or from the vinca alkaloid leurosine, in both cases via anhydrovinblastine. The insulin-stimulating vincoline has been isolated from the plant.
- Research uses
Despite the medical importance and wide use, the desired alkaloids (vinblastine and vincristine) are naturally produced at very low yields. Additionally, it is complex and costly to synthesize the desired products in a lab, resulting in difficulty satisfying the demand and a need for overproduction. Treatment of the plant with phytohormones, such as salicylic acid and methyl jasmonate, have been shown to trigger defense mechanisms and overproduce downstream alkaloids. Studies using this technique vary in growth conditions, choice of phytohormone, and location of treatment. Concurrently, there are various efforts to map the biosynthetic pathway producing the alkaloids to find a direct path to overproduction via genetic engineering.
C. roseus is used in plant pathology as an experimental host for phytoplasmas. This is because it is easy to infect with a large majority of phytoplasmas, and also often has very distinctive symptoms such as phyllody and significantly reduced leaf size.
In 1995 and 2006 Malagasy agronomists and American political ecologists studied the production of Catharanthus roseus around Fort Dauphin and Ambovombe and its export as a natural source of the alkaloids used to make vincristine, vinblastine and other vinca alkaloid cancer drugs. Their research focused on the wild collection of periwinkle roots and leaves from roadsides and fields and its industrial cultivation on large farms.
IV. Harvesting and Storage
Due to different blooming periods, fruit maturity also occurs at different times, and this is when the seeds of the plant can be harvested for sowing. Once the mature fruit turns black, the pericarp easily cleaves, meaning that the seeds will be lost. Therefore, the plant needs to be harvested when the pericarp turns yellow, and the black seeds can be vaguely seen.
