How to Grow Annual Vinca (Madagascar Periwinkle)

Annual vinca (Catharanthus roseus) is a tropical perennial that is grown as an annual in most regions. The foliage is dark green and leathery and the flowers and foliage resemble impatiens. But rather than being a shade lover, annual vinca is a perfect choice for sunny locations. Planted after the last frost date in your area, this is one of the most carefree annual flowers you can grow, with few serious disease or insect problems. Plant breeders have expanded the color palette of these drought-tolerant plants to include blooms in every shade of pink, rose, and lilac. The flowers attract butterflies.

Annual Vinca Care

Here are the main care requirements for growing annual vinca:

• Delay planting until there is no more danger of frost.
• Plant it in sandy loam soil in a location with full sun.
• Water only moderately when the top inch of soil feels dry.
• Apply a slow-release fertilizer at planting time.

Light

Annual vinca loves full sun. It will tolerate part shade but may become leggy in too much shade.

Soil

Vincas requires well-draining soil that is slightly acidic to neutral (pH between 6.0 and 7.0). If your soil is heavy. add compost before planting. Alternatively, plant vincas in raised beds or containers using a porous, well-draining potting mix.

Water

Watering too frequently is a common mistake with annual vinca. Water only when the top inch of soil feels dry to the touch. This is a plant that thrives in dry soil.

Temperature and Humidity

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; after all, these are hot weather annuals. A safe bet is to plant your vincas around the same time you set out your tomato transplants: when nighttime temperatures average 60°F. Annual vinca prospers in hot and humid weather.

The plant is not frost-tolerant and declines as the weather cools in fall.

Fertilizer

Apply compost to the bed, or use a slow-release fertilizer at planting time. Container-grown plants need more frequent feedings, as nutrients leech from the soil from more frequent watering.

Types of Annual Vinca

There are several series of annual vinca, varying in size, bloom time, resistance to heat, cold, disease, and other characteristics. Each series comes in a range of colors. Popular series include:

• 'Heatwave': The plants are extremely heat-tolerant and withstand cooler temperatures. They grow 10 inches tall with good branching.
• 'Cora XDR': This is a large variety with an upright mounding growth habit. The plants grow 14 to 16 inches tall with an 18- to 20-inch spread.
• 'Mediterranean': With a height of only 6 inches and a spread of up to 2 feet, this is a good choice for hanging baskets and window boxes.
• 'Pacifica': This early-flowering series includes the first true red annual vinca, 'Pacifica Red'. The plants grow 12 to 14 inches tall with large 2-inch-wide flowers.
• 'Tattoo': The flowers of this series stand out by their airbrushed look. The solid color of the flower petals has soft paintbrush-like strokes The upright plants grow 10 to 14 inches tall and 6 to 8 inches wide.
• 'Mega Bloom': Of all the annual vinca hybrids that are available as seeds, this is the one with the largest flowers. The plants grow 8 to 10 inches high and spread 10 to 12 inches. They were bred to resist heat, humidity, and fungal disease.
• 'Titan': This early-flowering, heat-tolerant series has large flowers and good branching. The plants grow 14 to 6 inches tall and 10 to 12 inches wide.
• 'Stardust': The flowers have a white starburst in the center. The plants grow 14 to 16 inches tall and wide. Stardust Orchid' was an All-America Selections (AAS) Bedding Plant Winner.

Pruning

Annual vinca is self-cleaning so no deadheading is necessary.

Propagating Annual Vinca

Before you set out to propagate annual vinca, check whether the variety is protected by a plant patent or trademark, which makes it illegal to propagate the plant in any form. If that's not the case, propagate annual vinca from stem cuttings in the early fall.

1. Cut 4 to 6 inches from a branch that does not have any flowers.
2. Remove the bottom leaves.
3. Place the cutting in water so the area where you removed the leaves is fully immersed. Keep the cutting in a place with bright light but out of direct sunlight.
4. Roots should begin to form within a month. Change the water if it turns murky or add more water to keep the bottom of the cutting immersed.
5. After roots have formed, transplant the cutting to a pot with potting mix.
6. Move the pot to a location with bright, direct sunlight, such as a west- or south-facing window. Keep the soil moist at all times.
7. The following spring, transplant it outdoors after all danger of frost has passed.

How to Grow Annual Vinca From Seeds

Because most annual vincas are hybrids, collecting seeds from your plants for propagation is not recommended, as those seeds won't produce plants that are true to the parent. Instead, purchase seeds from a seed company and start them indoors 12 to 15 weeks before your average last frost date.

1. Plant seeds 1/8 inch deep in pots filled with soilless seed-starting mix.
2. Keep the seeds evenly moist without overwatering them. At a temperature between 75 and 78°F, they will germinate in 14 to 21 days.
3. Place the pots in a location with plenty of direct sunlight or use grow lights for 16 hours per day, 
4. Harden off the seedlings for 10 days before transplanting them outdoors after the last spring frost.

Potting and Repotting

Use a pot with large drainage holes and fill it with well-draining potting soil. Vinca varieties range in height and spread so make sure to choose a container that is large enough. Don’t overcrowd the container even if it looks a bit sparse at the time of planting; annual vinca is a fast grower that will fill the empty space in no time.

Keep in mind that potted plants need more frequent watering than plants in garden soil. Especially hanging baskets are notorious for drying out fast.

Repotting during the plant’s single growing season isn’t necessary.

Common Pests & Plant Diseases

This plant has few serious disease or insect problems. In poorly draining soil, stem rot, leaf spot, and aster yellows may occur. Slugs and snails may also feast on the leaves. Annual vinca is deer-resistant and rabbit-resistant.

How to Get Vinca to Bloom

Bloom Months

Annual vinca typically blooms from July to September, often until the first fall frost.

What Do Annual Vinca Flowers Look and Smell Like?

Annual vinca bears single blooms with five petals that frequently touch or overlap.  There are pink, purple, red, white, magenta, and bi-colored varieties. Many varieties feature a contrasting eye. The flowers have a sweet smell.

How to Encourage More Blooms

Vinca is a prolific grower, but making sure it produces its darling, colorful flowers takes lots of sunlight and diligent watering. It won't bloom if its roots are waterlogged.

Common Problems With Annual Vinca

Brown Spots on Leaves

Damp conditions and a lack of airflow can cause fungal diseases which take the form of brown spots on the leaves. This problem is easily fixed by thinning out the plants as soon as the problem is noticed. Trim away all affected leaves with clean, sharp garden shears.

Yellow Wilted Leaves

If the leaves of your annual vinca are yellowing and wilted, it's likely your plant is getting too much water. Stick your finger into the soil. If it feels wet, there is too much moisture. Let the plant dry out and cut down on the watering.