Holiday cacti are short-day plants, meaning they will begin blooming as nights get longer and days get shorter. To initiate blooming, plants need to have at least 12 hours of continuous darkness for 5-6 weeks. Flower buds will not be set if the darkness is interrupted for too long (2+ hours). Once the flower buds have been set, day/night length will not affect flowering.  

Fortunately for us, our nights naturally get longer during the fall and winter. An easy way to get your holiday cacti to initiate flowering is to place them in a room that doesn’t receive artificial light at night, such as a spare bedroom or basement.

In addition to longer nights, plants need to be exposed to cooler temperatures. Keep plants in an area where daytime temperatures are 65-70° F and evening temperatures are 55-65° F. If they are kept in an area that is too warm, particularly at night, they may not bloom.

If you don’t want to deal with or have an area that gives plants enough darkness, you can try exposing them to nighttime temperatures around 55°F. This may also induce blooming, regardless of night length. Be careful, though. Temperatures below 50°F may cause flower buds to drop.

With a little work, you can enjoy the blooms of your holiday cacti this year and for many, many years to come.