Blooming in A Bed of Spines – Six Tips on Cactus Flowers

The Night-Blooming Cereus (Epiphyllum oxypetalum) at Tula House just flowered. Over the course of a week it produced dozens of fragrant blossoms, each lasting only a single night. The flowers, white as to reflect the light of the moon, didn’t have the chance to get pollinated, because our Brooklyn studio doesn’t have sphinx moths or bats.

Each morning, we swept up the fallen flowers, happy to witness this plant’s yearly ritual. It got us thinking about our other cacti – all of which do flower when mature and given the right conditions. But when they flower – that’s something we can never predict. While plants in the wild have blooming times that are well-catalogued, keeping them indoors is another thing entirely. 

For our fellow indoor gardeners, here are some things to consider when you think about your cactus flowers and how to get those conditions right.

• Balance – Cacti grown indoors need to strike a balance between water and sunlight before they are able to flower. During the summer, a good amount of water is needed to match the increased sun exposure and the energy the plant is putting into actively growing. In the winter, when plants like this typically go dormant, the plant will hardly want any water at all.

• Chill – Many cacti need a period of cold in order to bloom the next year. In a region with cold winters, a windowsill that gets plenty of sun is perfect. The plant will get a slight draft that could provide the needed chill.

• Nutrients – Sometimes a boost of nutrients in the beginning of a warm growing season will give a cactus what it needs to flower. Work a diluted cactus fertilizer into your watering routine. Avoid doing this in winter, especially if you are not seeing any new growth.

• Pollinators – Cacti have some of the widest range of pollinators in the plant kingdom. While Tula’s Epiphyllum oxypetalum would have attracted moths and bats in the wild, the Stapelia gigantea on the other side of the studio brought flies to the Arid Room, thanks to the noxious smell of its giant blooms.

• Age – Some cacti, like the gorgeous Opuntia miquelii, need some time before they flower. Specimens of this plant have lived 50 years before their first bloom appeared.
  
  
• Brevity – Have the camera ready. Most cacti bloom in quick bursts, firework shows that last for one day – or night.

From the overwhelming Stapelia gigantea to the dramatic Epiphyllum oxypetalum, every cactus bloom is a joy to witness. To get started on encouraging your own cacti to flower, check out the Plant Library.

Find your plant and learn what to expect from the flowers and when.

Happy caring.