The Purple Heart plant, known scientifically as Tradescantia pallida, is a popular choice for both indoor and outdoor gardeners due to its striking foliage. Its most defining characteristic is the rich, deep purple hue of its leaves and stems, which adds a vibrant splash of color to any setting. A common concern for many growers, however, is when this signature purple coloration begins to diminish, often turning a duller green.
The Purple Heart Plant’s Distinctive Color
The plant features elongated, pointed leaves and stems in vibrant purple, sometimes with a metallic sheen. Small, three-petaled pink or purple flowers occasionally emerge, contrasting with the dark foliage.
The intense purple color comes from anthocyanin pigments. These water-soluble pigments are responsible for red, purple, and blue hues in plants. Anthocyanins are produced by the plant, especially under intense light.
Chlorophyll, the green pigment essential for photosynthesis, is also present. In healthy plants, a high concentration of anthocyanins masks the green chlorophyll, allowing the plant to display its characteristic purple.
Primary Causes of Green Discoloration
The most significant factor contributing to the greening of a Purple Heart plant is insufficient light. The production of anthocyanin pigments, which give the plant its purple color, is directly influenced by light intensity. When the plant does not receive adequate light, it reduces its anthocyanin production, causing the green chlorophyll to become more prominent and the purple hue to fade.
Purple Heart plants thrive in bright, indirect light to full sun. Indoors, a south-facing window or a west-facing window with afternoon shade is ideal. Dimly lit rooms or shaded outdoor areas cause the vibrant purple to fade, often to a muted green or pale green-brown.
While light is the primary driver, nutrient imbalances can also play a role in the plant’s overall health and, consequently, its color vibrancy. Deficiencies in certain macronutrients like phosphorus or micronutrients like magnesium can impair the plant’s ability to produce pigments or maintain robust cell structures. However, these nutrient issues are less direct causes of greening compared to light deficiency, usually manifesting as overall poor growth before color loss.
Environmental stressors, such as extreme temperature fluctuations or consistent overwatering, can indirectly affect the plant’s ability to maintain its rich color. Plants subjected to prolonged stress may divert energy away from pigment production towards more immediate survival mechanisms. These stressors weaken the plant, making it less resilient and potentially impacting the visual quality of its foliage, though direct greening from these factors is less common than from light deprivation.
Steps to Restore and Preserve Purple Color
Optimizing light exposure is the most effective way to restore and preserve the vibrant purple. For indoor plants, relocate them to a brighter spot, ensuring at least six hours of bright, indirect light daily. If natural light is limited, supplementing with a grow light for 10-12 hours can enhance anthocyanin production and deepen the purple hue.
Outdoor Purple Heart plants perform best in locations receiving full sun for at least six hours daily, especially morning sun. If placed in a shadier spot, move them to a sunnier location. Gradual acclimation prevents leaf scorch, particularly if the plant was in a low-light environment.
Addressing nutrient needs through proper fertilization supports the plant’s vitality and strong coloration. During the growing season (spring and summer), feed the plant with a balanced liquid fertilizer diluted to half strength every 2-4 weeks. A general-purpose houseplant fertilizer, like 10-10-10 or 20-20-20, is suitable.
Consistent pruning helps maintain a compact, bushy form and encourages new, vibrantly colored foliage. Pinch back leggy stems to promote branching and dense growth. Ensuring the plant is in well-draining soil and receives consistent, but not excessive, watering prevents root issues that stress the plant and indirectly impact its color.