It is common for bougainvillea to not produce blooms during the summer.
August 30, 2024 - Although my choice was either hulking castor beans or candlestick plants, Mrs. G picked out a blooming bougainvillea this spring at the nursery and planted it on a trellis to block the west sun from our kitchen window. Unfortunately, it has not made a single bloom this summer and has not grown large enough to cover the window. She is not happy. What gives? First of all, bougainvillea are more sprawling shrubs than vigorous vines. They are also daylength sensitive, mostly producing blooms during the shorter days of spring and fall.
Bougainvillea, with their vibrant and striking bracts, are a favorite among gardeners looking to add a splash of color to their hot summer landscapes. However, despite our best efforts, these plants can sometimes stubbornly refuse to bloom during the summer. Understanding the reasons behind this frustrating phenomenon, particularly the plant’s response to daylight length and the long days of summer, plus a few horticultural tips, will hopefully keep marriages and gardens in harmony.
One key reason bougainvillea might not bloom during the summer is their sensitivity to daylight length. Bougainvillea are known as “short-day” plants, which means they typically initiate blooming when daylight hours begin to decrease. In their native environment, closer to the equator, these plants experience more consistent daylight lengths throughout the year. However, in Texas, during the summer, the long days can delay the flowering process.
During summer, with days stretching over 14 hours, bougainvillea might be reluctant to enter their flowering phase, instead focusing on vegetative growth. This response is a natural adaptation, as the plant perceives the extended daylight as a signal to continue growing leaves and stems rather than producing flowers. It is only when the days begin to shorten in late summer and early fall that bougainvillea typically respond by setting buds and blooming more profusely.
Light intensity also play significant roles in bougainvillea blooming. Bougainvillea are sun-loving plants, requiring a minimum of five to six hours of direct sunlight daily to encourage flowering.
Watering practices can also influence a bougainvillea’s response to long summer days. Overwatering during the summer can exacerbate the issue, as the plant might become too comfortable, focusing on leafy growth rather than blooming. Allowing the soil to dry out slightly between waterings can introduce a mild stress, encouraging the plant to flower as a survival mechanism.
Additionally, the type of fertilizer used can impact blooming during long summer days. Fertilizers high in nitrogen promote leafy growth, which is beneficial for the plant’s overall health but can suppress flower production. A slow-release fertilizer like Osmocote is ideal.
By understanding the relationship between daylength and plant growth, gardeners can better manage their plants to enjoy stunning blooms. While bougainvillea might be a bit temperamental in responding to the long days of summer, with a little extra care and attention, you can encourage them to still put on a spectacular show in your garden.
Greg Grant is the Smith County horticulturist and Master Gardener coordinator for the Texas A&M AgriLife Extension Service. He is the author of Texas Fruit and Vegetable Gardening, Texas Home Landscaping, Heirloom Gardening in the South, and The Rose Rustlers. You can read his “Greg’s Ramblings” blog at arborgate.com, read his “In Greg’s Garden” in each issue of Texas Gardener magazine (texasgardener.com), or follow him on Facebook at “Greg Grant Gardens.” More science-based lawn and gardening information from the Texas A&M AgriLife Extension Service can be found at aggieturf.tamu.edu and aggie-horticulture.tamu.edu.
