Thanksgiving and Christmas cacti set their flower buds when nights get long and cool. From early fall, give yours:

  • About 12 to 14 hours of uninterrupted darkness each night. A spare room you don't use in the evening works well. Even a lamp switched on for a while can delay the buds.
  • Cool nights, ideally around 50 to 55°F (10 to 13°C).
  • A little less water than usual, without letting the stems shrivel.

Keep it up for about six weeks, or until you see buds. Once they appear, try not to move the plant: sudden changes in light or temperature can make it drop its buds.

Fun fact: these aren't desert cacti at all. In the wild, they grow on trees in the mountain rainforests of southeastern Brazil.