Flowering Kale, or Ornamental Kale, is a popular cool-season plant valued for its striking appearance when many other garden displays have faded. This cultivar of Brassica oleracea is bred specifically for aesthetic appeal. Its large, dense rosettes feature frilly leaves splashed with vibrant shades of pink, purple, white, and red. This colorful foliage makes it a garden favorite, but its long-term classification often causes confusion.
The True Lifecycle of Flowering Kale
Flowering Kale is classified botanically as a biennial plant, meaning its natural life cycle spans two full growing seasons. During the first year, the plant focuses solely on producing the vegetative growth—the large, colorful rosette. It requires a period of cold temperatures, known as vernalization, to trigger its reproductive stage.
In the second year, the plant “bolts,” sending up a tall, thick flower stalk topped with small, yellow flowers. This bolting typically occurs in the spring as temperatures begin to rise consistently. Once the plant flowers and produces seed, it subsequently dies.
Despite its biennial classification, gardeners almost universally treat Flowering Kale as an annual. Its ornamental value ends when the bolting process begins, so cultivation focuses entirely on the first year’s leafy rosette, which provides color during the fall and winter months. Gardeners strategically plant it in the fall and remove it before spring warmth encourages the unattractive flower stalk to emerge.
Essential Cultivation Requirements
Ornamental Kale requires specific environmental conditions regarding soil and light to achieve a vibrant display. The plant performs best in full sun, which maximizes the intensity of its foliage colors. A minimum of six hours of direct sunlight daily is recommended, though it can tolerate partial shade.
The soil should be fertile, well-drained, and rich in organic matter to support robust growth. As a heavy feeder, the soil should be amended with compost or a balanced fertilizer at planting time. Optimal soil pH ranges from slightly acidic (around 5.8) up to neutral (near 7.5).
Consistent moisture is necessary, and plants should be kept well-watered, especially during establishment. Ornamental Kale requires approximately one inch of water per week. The plant cannot tolerate the persistent high heat of summer, as warm temperatures inhibit colorful foliage development and cause the central stem to elongate prematurely.
Maximizing Ornamental Display in Cool Weather
The aesthetic appeal of Flowering Kale is dependent on cool weather, which triggers vibrant color development. The colorful centers are leaves that produce pigments like anthocyanins in response to cold stress. This process begins when ambient temperatures consistently drop below 50°F (10°C) in early fall.
Light frost enhances the color intensity, making the colors more vivid and saturated. Established plants have exceptional cold tolerance, withstanding temperatures as low as 5°F (-15°C) for short periods. This allows gardeners to prolong the display well into the winter months.
Maintenance focuses on preserving the rosette and managing moisture. Remove yellowing or dead outer leaves to maintain appearance and improve air circulation. Protecting the central crown from excessive moisture prevents crown rot during cold, wet weather.
Fertilizing sparingly is recommended during the ornamental phase, as high nitrogen levels dilute the foliage color and encourage stem elongation. If a severe freeze is anticipated, covering the plants with mulch or a frost cloth offers protection.