Bougainvilleas are fast-growing and sprawling vines from South America that produce a showy display of color with minimal care. Their flowers are in fact small, white and tubular, and the plant's color actually comes from the surrounding modified leaves or bracts. Bougainvilleas are not frost tolerant but can be grown as houseplants or annuals in nontropical areas. In tropical and frost-free areas, bougainvillea vines will thrive in sunny conditions and produce year-round color.
Allow the surface of the soil around your bougainvillea vine to dry out between watering. Water aiming to thoroughly soak the soil around the roots. The watering interval will vary depending on the temperature and amount of wind. If your bougainvillea starts to wilt, water it immediately. Do not grow bougainvilleas in damp soil or areas prone to flooding.
Avoid light watering that only moistens the surface of the soil around your bougainvillea. Light watering encourages a shallow root system and makes your plant more vulnerable to drought and makes it not flower vigorously. Reduce the amount of water if your bougainvillea doesn't flower as a period of drought encourages the plant to bud.
Water large and established outdoor bougainvilleas only when the surface of the soil is completely dry. Large plants are drought resistant and reward occasional, heavy watering with more flowers. Do not neglect watering during the hot summer months. Even large bougainvilleas may need to be watered daily during hot, dry spells.
Water your potted bougainvillea as soon as the top inch of soil has dried out. Apply enough water to thoroughly soak all the soil. Make sure all excess water drains away. Do not keep potted plants in a dish or saucer as these trap excess water and can cause water logging and root rot. Reduce watering during the winter months to encourage your plant to rest. Aim to keep the soil barely moist during the coldest months of the year.