Madagascar periwinkle – A carefree annual flower

As I look back on the summer of 2021, one flower that I have grown to love is Madagascar periwinkle (Catharanthus roseus). Also known as Cape periwinkle or Annual vinca.  It’s a carefree annual flower with glossy green leaves and its flowers come in shades of pink, white and purple. Some varieties have contrasting eye colors in the center of the flower.

What else is special about Madagascar periwinkle? Well, there are so many features to love about this plant including drought tolerance, pest resistance, deer and rabbit resistance, no deadheading necessary, long bloom cycle and they provide nectar for migrating butterflies. While in most places, we treat this plant as an annual, in USDA gardening zones 9-11 it is a perennial. It’s my standout annual flowering plant for 2021.

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How to grow from seeds

Madagascar periwinkle can be started indoors from seed 12-16 weeks before the last frost. Ensure that seeds are completely covered with soil because Madagascar periwinkle needs darkness to germinate. Cover flats with either plastic wrap or a plastic dome to retain moisture. Madagascar periwinkle will germinate in five to seven days in temperatures above 70°F. After seedlings emerge, remove the dome and place under bright direct light (grow lights are best). When outdoor soil temperatures reach a minimum of 60°F, Madagascar periwinkle can be planted outdoors (after the last frost date for your area). Once the seedling emerges, it will take anywhere from 1-3 months for the flowers to appear.

Before planting outdoors, it’s important to “harden off” the seedlings. Hardening off is the process of gradually acclimating the plant to the outdoors. Hardening off can be done in a cold frame or by simply placing the plants outdoors for a couple of hours each day for one to two weeks. For a full guide on starting plants from seeds, see my blog post titled “The complete guide to starting plants from seeds indoors”.

How to care for Madagascar periwinkle

While Madagascar periwinkle is a carefree annual flower, there are a few important growing tips. Whether you purchase bedding plants or start plants from seeds, plant outdoors after all danger of frost has passed. Madagascar periwinkle will continuously bloom until the first cold spell. Flowers will begin to fade and curl when temperatures drop below 50°F.

• Light:  Full sun (6 hours of sunlight a day) to part shade.
• Soil:  Soil that is fertile, well-drained and amended with organic matter (e.g. the addition of compost and/or manures). Compost can be made at home or purchased from a garden center. For information on making compost at home, reference my blog titled “Recipes for Compost”. It is best to work compost into the soil in the fall for a spring planting.
• Spacing: Follow the guidelines on the back of the seed package for plant spacing. The thing to remember is that Madagascar periwinkle will spread 10-20 inches and grow equally tall.
• Water:  Moderate watering, remember this is a drought tolerant plant. However, if planted in containers, more frequent watering is needed.
• Fertilizing: Madagascar periwinkle is not particular about fertilizer. Applying compost to the bed or a slow-release fertilizer at planting time is recommended.
• Companions: Good companions in a container include verbena, geranium, and angolenia.
• Other characteristics:
  • Deadheading is not necessary
  • Drought and heat tolerant
  • Disease resistant
  • Deer and rabbit resistant
  • Madagascar periwinkle a is toxic to cats, dogs, and people

In your garden, use Madagascar periwinkle as a bedding, border, or container plant. They also do well in window boxes.

Propagating

Take cuttings of Madagascar periwinkle in early fall. Remove leaves on the bottom third of the stalk. Root the cuttings in water. Approximately 8 weeks before the last frost in your area, plant the cuttings in potting soil. Plant outdoors after all danger of frost has passed. Remember to acclimate the plants outdoors for a week before transplanting them into the ground. Acclimating is the process of slowly allowing the plant to adapt to the outdoors. Place the plants outdoors for 1 hour/day the week prior to outdoor planting.

Saving seeds

I always find it fascinating to learn about the various methods by which plants form their seeds. With Madagascar periwinkle, seed pods are formed along the stalk of the flower. These seedpods can be taken off the stalk and placed in a paper bag until they are completely dried out. Once dried out, open the pod and there should be a number of small black seeds inside.

Ideas for how to use Madagascar periwinkle in your garden

If you haven’t tried Madagascar periwinkle, I encourage you to do so. It’s the most carefree annual flower in my garden. Here are some additional posts you may enjoy

• Using first and last frost dates to plan your garden
• Profusion Zinnias: An awesome flower to grow
• Growing and caring for Zinnias, the complete guide
• Saving Zinnia Seeds
• Growing and Caring for Marigolds, the complete guide

References

• Cornell University – Vinca
• Missouri Botantical Garden – Catharanthus roseus