Bougainvillea, a tropical plant native to South America, is celebrated for its vibrant and colorful bracts. These modified leaves, which surround small true flowers, display a wide range of hues including pink, magenta, purple, red, orange, and white. Its vigorous growth habit allows it to quickly cover spaces, making it a popular choice for adding a burst of color to various settings.
Is Bougainvillea Suited for Colorado’s Climate
Bougainvillea thrives in warm, sunny environments and is suited for USDA hardiness zones 9 to 11. Most of Colorado falls within USDA hardiness zones 3 to 7, meaning the plant cannot survive outdoors year-round due to frost and cold temperatures. Colorado’s dry air also presents a challenge for this tropical species.
Despite these climatic limitations, bougainvillea can be successfully grown in Colorado with specific care. It is cultivated as a tender perennial, meaning it can be enjoyed outdoors during the warmer months and brought indoors for winter protection. Growing bougainvillea in containers is the primary method to achieve success in this region, allowing for easy relocation as seasons change. This approach mitigates the challenges posed by Colorado’s cold winters and dry conditions.
Growing Bougainvillea Successfully in Colorado
Light Requirements
Bougainvillea needs abundant direct sunlight to produce its signature vibrant bracts. For optimal blooming, the plant requires at least six hours of full sun daily. Placing container-grown bougainvillea outdoors in intense, unfiltered sunlight during summer is ideal. Insufficient light can lead to reduced color intensity and fewer blooms.
Watering Needs
Proper watering is crucial for encouraging bougainvillea to bloom, as it prefers a specific drying cycle. Allow the soil to dry out significantly between waterings to encourage flowering. Overwatering can lead to root rot and inhibit bloom production. Watering needs vary depending on temperature, humidity, and the container’s size and material, with larger pots and hotter conditions requiring more frequent checks.
Soil and Potting
A well-draining potting mix is essential for bougainvillea to thrive, preventing waterlogged conditions that can harm roots. Terracotta containers are beneficial due to their porous nature, allowing better air circulation and moisture evaporation from the soil. Bougainvillea prefers to be slightly root-bound, blooming more profusely when its roots are somewhat restricted within the pot. Select a pot size appropriate for the plant’s current root mass to encourage better flowering.
Fertilization
During the active growing season (spring through summer), bougainvillea benefits from regular fertilization to support its blooming cycle. Use a balanced fertilizer or one with a higher phosphorus content to promote flower production. Fertilize every two to four weeks. As the plant transitions towards dormancy in late summer or early fall, gradually reduce fertilizer frequency and concentration, eventually ceasing altogether.
Pruning for Shape and Bloom
Pruning bougainvillea helps manage its size and shape, which is particularly important for container-grown plants. Light pruning throughout the growing season encourages new flowering branches. Pinching back tender branch ends promotes denser foliage and more prolific blooming. A more significant pruning can be done before bringing the plant indoors for winter dormancy, preparing it for colder months and maintaining its overall form.
Preparing Bougainvillea for Colorado Winters
Protecting bougainvillea from Colorado’s cold temperatures is crucial for its survival. Before the first frost arrives, typically in late September or early October, move the plant indoors. Temperatures consistently below 40 degrees Fahrenheit can damage or kill the plant.
Once indoors, bougainvillea enters a semi-dormant or dormant state. Ideal indoor conditions for overwintering involve a cooler environment (45-60°F) with reduced light. During this period, the plant’s metabolic rate slows significantly.
It is normal for bougainvillea to shed most, if not all, of its leaves during indoor dormancy. This leaf drop is a natural response to environmental changes and reduced light. Minimal watering is required, just enough to prevent the soil from drying out completely. Fertilization should be completely withheld during dormancy.
In spring, once frost danger passes and outdoor temperatures consistently remain above 50°F, bougainvillea can be gradually transitioned back outdoors. Begin by placing it in a sheltered, partially shaded location for a few days to acclimate it before moving it to its full sun position. This gradual reintroduction helps prevent shock and prepares the plant for vigorous summer growth.
Addressing Common Bougainvillea Challenges
Lack of blooms is a common issue for bougainvillea growers, often stemming from specific environmental factors. Overwatering, excessive nitrogen fertilizer (which promotes leafy growth over flowers), or insufficient direct sunlight are frequent causes for poor blooming. Ensuring adequate sun and a drying cycle between waterings can often resolve this.
Leaf drop, while alarming, can be a normal occurrence for bougainvillea, especially during environmental transitions or stress. When moving the plant indoors for winter or experiencing sudden changes in temperature or light, some leaf shedding is expected. Overwatering or underwatering can also lead to leaf loss, indicating a need to adjust watering.
Pests like aphids and mealybugs can occasionally infest bougainvillea, though they are generally not severe problems. These small insects can typically be managed with organic control methods, such as a strong water spray or insecticidal soap. Diseases are less common for bougainvillea, but ensuring good air circulation and avoiding prolonged wet foliage can prevent potential fungal issues.