Poinsettia Bract Bloom - Ask Extension
In tropical climates do poinsettias bloom continuously or bloom throughout the year or is bloom time only late fall/early winter.
Knowledgebase
Poinsettia Bract Bloom #890989
Asked December 23, 2024, 12:40 PM EST
In tropical climates do poinsettias bloom continuously or bloom throughout the year or is bloom time only late fall/early winter.
Baltimore City County Maryland
Expert Response
Where they are native, they only bloom in winter. Poinsettias are actually shrubs or small trees in the wild, and are native to Mexico and Guatemala, in tropical forests along the Pacific coast. They only occur from low to mid-level elevations on those mountain slopes, so aren’t adapted to cold, which is one reason why they are houseplants in our area.
When kept alive all winter and grown outdoors (in a container) in the summer, they are perennials and can bloom every year, but they are short-day plants, meaning that they bloom while the day length is short and the nights are long. Since we can’t keep them outside to experience naturally short days here in Maryland, gardeners and the nurseries producing the plants for sale need to take this into consideration when growing them indoors or in greenhouses. Even though typical room lighting used after sunset during those shorter autumn/winter days is generally not bright enough to support sufficient photosynthesis, it is enough for the plant to detect and respond to in terms of flowering, which is why poinsettias kept growing for the following year may not bloom "on time."
The colorful parts we view as petals are actually bracts, which are specialized leaves that act like petals to draw attention to the tinier true flowers so pollinators can find them. Once these true flowers are spent, the bracts gradually lose their color and turn green again. Sometimes poinsettias will keep good bract color well into February before fading, but it can depend on plant vigor and health and potentially the genetics of the cultivar as well.
Miri
When kept alive all winter and grown outdoors (in a container) in the summer, they are perennials and can bloom every year, but they are short-day plants, meaning that they bloom while the day length is short and the nights are long. Since we can’t keep them outside to experience naturally short days here in Maryland, gardeners and the nurseries producing the plants for sale need to take this into consideration when growing them indoors or in greenhouses. Even though typical room lighting used after sunset during those shorter autumn/winter days is generally not bright enough to support sufficient photosynthesis, it is enough for the plant to detect and respond to in terms of flowering, which is why poinsettias kept growing for the following year may not bloom "on time."
The colorful parts we view as petals are actually bracts, which are specialized leaves that act like petals to draw attention to the tinier true flowers so pollinators can find them. Once these true flowers are spent, the bracts gradually lose their color and turn green again. Sometimes poinsettias will keep good bract color well into February before fading, but it can depend on plant vigor and health and potentially the genetics of the cultivar as well.
Miri
