The term “Vinca” often confuses gardeners because it refers to two distinct groups of flowering plants with vastly different bloom characteristics. While both are popular choices for landscape color, their flowering schedules are not alike. Understanding which plant a gardener is cultivating is necessary to anticipate when its flowers will appear and for how long the display will last. These two categories have different origins, growth habits, and temperature requirements that directly influence the timing and duration of their flowering.
The Critical Distinction Between Vinca Varieties
The two plants commonly known as Vinca belong to different genera and possess fundamentally different growth habits. The first type is the true periwinkle, belonging to the genus Vinca (Vinca minor and Vinca major). These are perennial, cold-hardy groundcovers with trailing stems that root as they spread, forming a dense mat of evergreen foliage.
The second plant is the annual Vinca, scientifically known as Catharanthus roseus (Madagascar Periwinkle). This type is a tropical perennial grown as an annual in most temperate climates, exhibiting an upright, bushy growth habit. Catharanthus roseus is used as a bedding plant and is prized for its ability to thrive in hot, sunny conditions. Differentiating between the low-growing, perennial vine and the upright, annual bedding plant is the first step in predicting the bloom cycle.
When Groundcover Vinca Blooms
The perennial groundcover species, Vinca minor and Vinca major, are known for their early arrival of color in the garden. Their bloom period begins in early to mid-spring, often starting as early as March and extending through May or June, depending on the climate. This flowering is usually a short, intense burst, carpeting the ground with small, star-shaped flowers in shades of blue, purple, or white.
The onset of the bloom is tied to the warming temperatures of spring, which triggers the plant’s growth cycle after winter dormancy. Environmental factors, such as an early warm spell, can shift the blooming window forward, but the overall duration of the main flush remains brief. While the plant’s evergreen leaves provide year-round interest, the primary floral display lasts for only a few weeks. Some cultivars may produce sporadic flowers intermittently throughout the summer or fall, but this is minor compared to the concentrated spring bloom.
When Annual Vinca Blooms
The annual Vinca, Catharanthus roseus, is valued for its nearly continuous and extended flowering season. Its bloom cycle begins much later than the groundcover variety, starting in late spring or early summer after the danger of frost has passed and soil temperatures have warmed sufficiently. This plant requires high air and substrate temperatures, often preferring daytime temperatures around 82°F to thrive and initiate flowering.
Once established, the annual Vinca produces abundant, showy flowers that continue without interruption throughout the entire summer season. This continuous production makes it a popular choice for consistent color in garden beds and containers. The flowering only ceases when the plant is killed by the first hard frost of autumn or early winter. Its tolerance for heat and dry conditions helps maintain this long display when many other annuals might struggle.