The Night Blooming Cereus is a collective name for several cactus species, including the Epiphyllum oxypetalum (Queen of the Night) and the desert-dwelling Peniocereus greggii. These plants are celebrated because their flowers only open after sunset, lasting just a few hours. This nocturnal timing is an evolutionary adaptation, attracting specific nighttime pollinators like bats and hawk moths to ensure reproduction. Observing the opening of the bloom is often a special, once-a-year event for enthusiasts.
Preparation for the Spectacle
The single night of blooming is preceded by a preparation phase lasting several weeks, beginning with the formation of a tiny flower bud. For Epiphyllum varieties, these buds emerge from the scalloped indentations along the edges of the flattened, leaf-like stems, which must be mature to produce a flower. The tiny nub grows slowly for the majority of the period, making it difficult to predict the exact night of the opening.
The final week provides clear visual indicators that the bloom is imminent. In the few days leading up to the bloom, the flower bud experiences a rapid growth spurt, swelling dramatically in size. The bud’s long stem bends, positioning the flower parallel to the ground instead of pointing upward. On the day of the opening, the outer protective segments, called bracts or sepals, appear plump and wavy, sometimes showing a slight pink or reddish tint.
The Night of the Bloom Opening and Peak
The rapid opening of the Cereus flower begins as the sun sets and the plant registers the onset of darkness. Around 7:00 PM to 8:00 PM, the tightly furled outer sepals begin to slowly peel back, starting a kinetic process that can sometimes be observed. As the evening progresses, the flower accelerates its unfolding, a process that is typically complete within a few hours.
By the late evening, often between 10:00 PM and midnight, the flower reaches its peak, fully unfurling into a massive, waterlily-like blossom. The fully open flower can measure up to 12 inches long and 8 inches wide, with numerous pure white petals surrounded by thinner, yellowish or pinkish outer sepals.
This peak state is accompanied by an intense, sweet fragrance, which serves to attract its nocturnal pollinators and can easily scent an entire room. The powerful aroma is caused by specific volatile organic compounds, such as benzyl salicylate, released into the cool night air. This brief peak is the plant’s only window for pollination, lasting only a few hours. The structure is designed for a single night of reproductive activity.
The Aftermath and Ephemeral Nature
The Night Blooming Cereus flower begins its wilting process immediately upon sensing the first light of dawn. This light-sensitive reaction causes the plant to rapidly collapse the structure of the bloom. The petals and sepals quickly lose their rigidity, causing the flower to shrivel and close up before the sun fully crests the horizon.
By mid-morning, the display has transformed into a spent bloom. The wilted flower remains attached to the stem for a short time before drying out and dropping off naturally. If the flower was successfully pollinated during its brief open period, the base of the bloom will begin to swell, eventually developing into a fruit over the subsequent weeks or months. For species like Epiphyllum oxypetalum, the result is an oblong, purplish-red fruit.