The bougainvillea is a striking tropical plant known for its vibrant, paper-like bracts that provide intense color in warm climates. Native to South America, this plant needs specific care to thrive, especially when grown in containers or non-native soil where nutrients are limited. Achieving the spectacular display of color requires a strategic approach to fertilization. Understanding the plant’s unique nutritional demands ensures energy is directed toward producing abundant flowers instead of just foliage.
Essential Nutritional Requirements
The foundation for maximum bougainvillea blooms is selecting a fertilizer low in nitrogen (N) but high in phosphorus (P) and potassium (K). This precise ratio of macronutrients ensures the plant performs optimally. The NPK ratio for blooming should have the middle and third numbers significantly higher than the first.
Nitrogen is the nutrient primarily responsible for vegetative growth, promoting lush, green leaves and stems. Applying high nitrogen fertilizer will cause the bougainvillea to produce extensive foliage at the expense of its colorful bracts. Phosphorus aids in flower formation and root development, while potassium strengthens the plant’s overall health and resilience to stress.
Bougainvillea, especially those grown in pots, benefit from supplemental micronutrients. Iron and magnesium are important, as deficiencies can cause the leaves to turn yellow, a condition known as chlorosis. Providing chelated iron helps prevent this yellowing, ensuring the foliage remains deep green and healthy enough to support flowering.
Recommended Feeding Schedule
The timing of fertilization is important for maximizing the plant’s blooming potential. Bougainvillea requires consistent feeding during its active growing season, which spans from early spring through the summer months when the plant is actively producing new growth.
For container-grown plants, apply a liquid fertilizer monthly, or use a slow-release granular product every six to eight weeks. Established in-ground bougainvilleas are lighter feeders and benefit from an application every four to six weeks during this peak season. Begin this regimen just as new growth starts to appear in the spring.
As the season transitions into fall, significantly reduce the feeding schedule. This reduction signals the plant to slow its vegetative growth. During winter or any period of dormancy, halt fertilization entirely to prevent nutrient waste and discourage tender new growth susceptible to cold damage.
Encouraging Abundant Flowering
To push the bougainvillea toward abundant flowering, utilize products designed as bloom boosters. These fertilizers are heavily weighted toward phosphorus and potassium, featuring the low-nitrogen formula the plant prefers. Specialized bougainvillea fertilizers or high-phosphorus formulas are excellent choices for encouraging flower production.
When applying granular fertilizers, spread the product evenly around the plant’s drip line to prevent fertilizer burn near the main trunk or stem. For liquid feeds, follow the dilution instructions precisely to avoid over-fertilization, which can harm the fine roots.
A final technique that works alongside proper low-nitrogen feeding is the controlled withholding of water. Bougainvillea are drought-tolerant and respond to mild water stress by shifting energy away from leaf production and into flower bud formation. Allowing the soil to dry out between deep waterings during the bloom cycle can stress the plant enough to trigger a spectacular flush of color.