Bougainvillea, known for its vibrant, paper-like bracts, is a popular choice for adding color to gardens. While generally robust, owners often observe leaf shedding, indicating various underlying issues. This guide explores common factors contributing to bougainvillea leaf loss.
Normal Leaf Drop Patterns
Some leaf shedding is a natural part of a bougainvillea’s life cycle and is not always a problem. Bougainvilleas can be semi-deciduous, shedding some or all leaves, especially in cooler climates or during dry spells during seasonal dormancy. Older leaves also yellow and drop as new growth emerges.
Watering Problems
Watering practices frequently cause leaf drop in bougainvillea, due to both underwatering and overwatering. Bougainvillea prefers its soil to dry out between waterings, and established plants tolerate drought. Underwatering leads to wilting, crispy leaves, and eventual shedding due to water stress. Deep, infrequent watering is recommended, allowing the soil to dry thoroughly before the next application.
Conversely, overwatering is a common issue. Excess moisture can lead to root rot, hindering nutrient and water absorption. Symptoms include yellowing leaves that drop, stunted growth, and overall decline. Ensure well-draining soil and pots with adequate drainage holes to prevent waterlogging.
Light and Temperature Stress
Inadequate light and extreme temperatures stress bougainvillea, causing leaf loss. Bougainvilleas require abundant sunlight, ideally six or more hours daily, to thrive and produce colorful bracts. When deprived of sufficient light, plants may exhibit sparse foliage, reduced blooming, weak growth, and eventual leaf drop. Moving the plant to a brighter location or ensuring ample direct sunlight mitigates this issue.
Bougainvilleas are sensitive to sudden or prolonged cold temperatures, inducing leaf shedding. Temperatures below approximately 10°C (50°F) can cause yellowing and leaf drop. Protecting plants from cold snaps, such as by covering them or moving potted specimens indoors, is important. While they tolerate heat well, extreme heat combined with water stress also contributes to leaf issues.
Nutrient Imbalances
Leaf yellowing and drop can stem from nutrient imbalances, including deficiencies and excesses. Nitrogen deficiency commonly causes older leaves to yellow. Other micronutrient deficiencies, such as iron or magnesium, also cause discolored foliage, appearing as pale green leaves with darker veins or spotted yellow patterns.
To address nutrient needs, a balanced fertilizer low in nitrogen is advised for bougainvillea, as excessive nitrogen promotes leafy growth at the expense of flowers. Ensuring essential micronutrients is also important. Conversely, too much fertilizer can lead to root burn and leaf loss, requiring careful application according to instructions.
Pest Infestations and Diseases
Pest infestations and certain diseases weaken bougainvillea, leading to leaf drop. Common pests include aphids, mealybugs, and spider mites. Aphids and mealybugs suck sap, causing leaves to yellow, distort, and drop, often leaving sticky residue. Spider mites cause stippling on leaves, which may yellow and fall off in severe infestations, often with fine webbing. Regular inspection of leaves, especially their undersides, helps in early detection. Organic treatment options like neem oil or insecticidal soap manage these pests.
Bougainvillea can also be affected by fungal diseases such as root rot and leaf spot. Root rot causes wilting and yellowing leaves. Leaf spot diseases appear as discolored spots that enlarge and cause premature leaf drop, particularly under wet conditions and poor air circulation. Ensuring good air circulation around the plant and proper watering practices prevent these diseases.
Transplant Shock and Other Stressors
Bougainvillea can experience leaf drop from various stressors, including transplant shock and sudden environmental changes. Transplant shock is a common reaction when bougainvillea are moved or repotted, as they are sensitive to root disturbance. Symptoms include wilting, yellowing, and shedding of leaves, as damaged roots struggle to absorb enough water. Minimizing root disturbance, gentle handling, and immediate, thorough watering after transplanting reduce shock severity.
Abrupt shifts in environmental conditions, such as moving a plant from outdoors to indoors or vice versa, also trigger temporary leaf loss as the bougainvillea adjusts. Significant changes in light, humidity, or temperature induce this stress. Physical damage, such as from rough handling or severe pruning, also leads to localized leaf shedding. Providing a stable environment and gradually acclimating the plant to new conditions helps it adapt without excessive leaf drop.