Bougainvillea, known for its vibrant, papery bracts, is a tropical plant that can be grown indoors, but success requires replicating its native environment. This vine-like shrub thrives in intense sun and heat, conditions often difficult to maintain inside a home. Successful indoor cultivation requires high light, precise watering, and a necessary winter rest period. The reward is a splash of exotic color that can brighten the home.
Creating the Ideal Indoor Climate
The greatest challenge to growing bougainvillea indoors is meeting its requirement for intense, direct sunlight. To produce colorful bracts, the plant needs a minimum of six hours of full sun daily; eight hours is ideal for maximum blooming. A south-facing window is usually the only location that provides this necessary duration and intensity of light.
If natural light is insufficient, the use of supplemental lighting becomes necessary to prevent spindly growth and leafiness without flowers. High-output LED or fluorescent grow lights should be positioned close to the plant to provide the required intensity, especially during shorter winter days. Bougainvillea prefers warm conditions, with daytime temperatures ideally ranging between 65°F and 80°F.
The plant should be kept away from cold drafts and exterior windows during winter. While it enjoys warmth, a slight drop in nighttime temperatures, closer to 60°F, can encourage the development of flower buds. Do not place the plant directly near heating vents, which cause excessively dry air and leaf drop.
Choosing the Right Container and Soil
The container must prioritize drainage, as bougainvillea is susceptible to root rot in soggy conditions. Pots must have large drainage holes to ensure excess water flows away freely after irrigation. Terracotta or unglazed clay pots are recommended because their porous material helps wick moisture away from the soil, preventing waterlogging.
Bougainvillea performs best when its roots are slightly restricted. This root constraint encourages the production of blooms over vegetative growth. When repotting, move the plant into a container only one size larger than its current pot to maintain this desired state.
The potting medium itself should be lean and well-draining, contrasting with the rich, moisture-retentive soil favored by many other houseplants. A suitable mix can be created by combining standard potting soil with amendments like perlite, coarse sand, or a cactus mix to increase aeration. Avoiding mixes with high levels of peat moss is important, as peat can hold too much water and lead to root problems.
Routine Care and Seasonal Pruning
Bougainvillea is drought-tolerant and thrives on a specific watering regimen involving periods of dryness. During the active growing season, allow the top few inches of soil to dry out completely before watering thoroughly until water drains from the pot’s bottom. A degree of water stress stimulates the plant to produce its colorful bracts.
Fertilization should be consistent but measured during the spring and summer active growth period. Apply a balanced, slow-release fertilizer or a water-soluble formula every four to six weeks. Use a feed that is not high in nitrogen, as too much nitrogen promotes lush foliage at the expense of flowers.
Pruning is required for an indoor bougainvillea, as the plant naturally grows into a large, sprawling vine. Aggressive pruning maintains a manageable size and shape, often training it as a small shrub or bonsai. Since bougainvillea produces blooms on new wood, pinching back the tips of stems after each flush of color encourages new growth and more flowers.
Managing Winter Dormancy
When daylight hours shorten in the fall, bougainvillea enters a period of semi-dormancy. Leaf drop is a normal reaction to the reduced light intensity indoors. The goal during winter is to let the plant rest and conserve energy until brighter conditions return.
The winterizing protocol requires reduced care; stop fertilizer application until early spring. Watering frequency must be drastically reduced, providing only enough moisture to prevent the root ball from shriveling. Overwatering is a common mistake during this rest period and leads to root rot in cooler, darker conditions.
Move the plant to a slightly cooler location, ideally one that stays above 50°F, to aid in inducing dormancy. Even in a cooler spot, it should remain the brightest spot available to prevent excessive leaf loss. When the plant shows new green growth in late winter or early spring, gradually resume normal watering and fertilization.