The foliage is dark green and leathery. Depending on the variety, fast-growing vinca is 6 to 18 inches tall with a similar spread. Annual vinca plants bear single blooms with five petals that frequently touch or overlap from early summer until the first frost. 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. No matter your preference, all are attractive to butterflies and are rabbit-resistant. All parts of the annual vinca plant are toxic to dogs, cats, and people. Annual vinca is best grown in a sandy loam soil in a full sun location. Although tolerant of drought, it will perform best with a weekly water soak rather than sprayed from overhead. Vincas are free-flowering and self-cleaning, and no deadheading is necessary. This is one of the most carefree annual flowers you can grow, with few serious disease or insect problems. In poorly draining soil, stem rot and leaf spots may occur. Slugs and snails may also feast on the leaves.
Light
Annual vinca loves full sun. It will tolerate part shade but may become leggy if there is too much shade.
Soil
Vincas demand well-draining soil. Add compost or grit to your heavy soil; alternatively, plant vincas in raised beds or containers with a porous, well-draining potting mix.
Water
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.
Temperature and Humidity
This plant thrives in hot and humid weather. It will languish a bit if planted too early in the cool spring, and will begin to diminish 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 as water drains.
Types of Annual Vinca
Top varieties of annual vinca include:
‘Cooler’ series: A good choice for gardeners with cool summers. ‘Heatwave’ series: Plants have a very compact growth habit. ‘Mediterranean’ series: Plants trail to 2 feet; use in containers and hanging baskets. ‘Pacifica’ series: An early bloomer. ‘Soiree Double White’: A novelty in the vinca world, this variety produces double flowers for a full, lush look. ‘Stardust series’: Flowers feature a white starburst in the center. Look for the All-America Selections’ award-winning “Stardust Orchid.”
Propagating Annual Vinca
This plant can be easily propagated by taking cuttings in early fall. Root them in water over the winter. Plant the rooted cuttings in potting soil in late winter and grow them into nursery plants to set out when the weather warms the following spring.
How to Grow Annual Vinca From Seeds
The newer vincas are easier to start from seed than their predecessors. They do take time to flower, however, so start seeds indoors 12 to 16 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 Fahrenheit. Make sure to harden off seedlings for a week to 10 days prior to planting in the garden.
How to Get Vinca to Bloom
Vinca is a prolific grower, but making sure it produces its darling, colorful flowers takes a couple of factors: As long as you’re addressing those two factors, vinca will bloom all season, no deadheading is necessary.
Common Problems With Annual Vinca
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.
