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Annual Vinca Flowers, the Madagascar Periwinkle

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Annual Vinca Flowers, the Madagascar Periwinkle

Many vincas have a contrasting eye.

Photo © Troy McKaskle
Annual vincas aren’t new or flashy flowers on the gardening scene, but recent cultivar developments warrant a new examination of this common bedding plant. Horticulturists have been hard at work bringing us new colors in plants with showier flowers that are easier to start from seed. In a plant that was already reliably drought-tolerant and pest-free, what more could we ask?

Latin Name:

Annual vinca plants are of the genus Cartharanthus, a member of the Apocynaceae family. This is a case where paying attention to the Latin name is helpful: you must distinguish the annual vinca flower from the perennial vinca minor vine, which forms a dense mat and can be invasive.

Common Names:

Madagascar periwinkle

Zone:

Grow as a hot weather annual in all growing zones.

Size:

8 to 18 inches tall, spreading one to two feet

Exposure:

Full sun is best, although some afternoon shade is fine.

Bloom Period:

Early summer until first frost

Description:

The foliage of vinca plants is dark green and leathery looking. Vinca plants bear single blooms with five petals that frequently touch or overlap. Many varieties feature a contrasting eye. If you haven’t included vincas in your garden for a while, you should check out the expanded color palette that now includes blooms in every shade of the pink, rose, and lilac spectrum. Peach and white flowers are also available.

Planting:

  • The new vincas on the market are easier to start from seed than their predecessors. They do take time to flower however, so start seeds indoors at least 10 weeks before your average last frost. Cover the seeds enough to ensure darkness, and use supplemental heat if necessary to provide an ideal germination temperature of 75 degrees F.
  • Don’t rush to put out vinca plants in the spring. Plants set out too early in cold, wet soil will deliver a sickly performance. A safe bet is to plant your vincas around the same time you set out your tomato transplants: when evening temperatures average 60 degrees F.
  • Vincas demand well-draining soil. Add compost or grit to your heavy soil; alternatively, plant vincas in raised beds or containers.

Maintenance:

  • Vinca is drought tolerant, but if you notice the leaves start to curl, it’s time for a drink.
  • Vincas are free-flowering and self-cleaning, and no deadheading is necessary.
  • Fertilize vincas every two weeks with a balanced flower fertilizer to help these performers keep up the blooming momentum.

Design Tips:

  • Buy a six-pack of vinca plants as a filler for any blank sunny spot in the garden border where your perennials haven’t matured yet.
  • The low care nature of vinca plants helps them succeed in window boxes and other garden containers.
  • Bring out the contrasting eye of the vinca flower by pairing them with a flower that matches the flower’s eye. For example, plant white vincas with a burgundy eye beside burgundy zinnias.

Varieties:

  • Cooler series: A good choice for gardeners with cool summers.
  • Heatwave series: Plants have a very compact growth habit.
  • Mediterranean series: Plants trail to two feet; use in containers and hanging baskets.
  • Pacifica series: An early bloomer.
  • Stardust series: Flowers feature a white starburst in the center. Look for the All-America Selections award winning ‘Stardust Orchid.’
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