Yes — short, cool days are important for Christmas cactus to flower, but it doesn’t need a full 12 hours of complete darkness in the strict sense. Here’s how it works:
How Flowering is Triggered
- Species: Schlumbergera spp.
- Trigger: A combination of short day length and cool nights
- Day length: About 10–12 hours of light or less per day for 6–8 weeks
- Night temperature: Cooler nights around 12–15 °C (55–60 °F) help buds form
Practical Tips
- Place in a bright room but away from strong artificial light at night. Even a small lamp can interfere with bud formation.
- Reduce watering slightly when buds start forming — soil should be slightly moist, not wet.
- Do not move the plant once buds appear; sudden changes in light or temperature can cause buds to drop.
💡 Essentially, it’s day length-sensitive, not strictly “12 hours of darkness,” but 12–14 hours of uninterrupted darkness each night in autumn is ideal for reliable flowering.
