Poinsettias are known for their vibrant red, pink, or white bracts, which are often associated with the holiday season. If you want to enjoy your poinsettia’s beautiful blooms during the next holiday season, it’s important to follow a specific care routine that encourages the plant to re-bloom. One key element of this process involves placing the poinsettia in the dark for a set period each day to trigger its blooming cycle. But when exactly should you start this process, and how long does it need to be done? Here’s everything you need to know about when and how to put your poinsettia in the dark.
Understanding the Blooming Cycle of Poinsettias
Poinsettias are photoperiod-sensitive plants, meaning they rely on the length of daylight they receive to trigger blooming. They need long nights (around 12 to 14 hours of darkness) to set buds and develop their colorful bracts. This natural process of blooming is influenced by the changing seasons, which is why the plant’s flowering can be synced with the holiday season.
To get your poinsettia to bloom by the next holiday season, it needs a period of darkness that mimics the shorter days of autumn. Without this special light manipulation, the plant won’t produce the vibrant blooms you’re expecting.
When to Start the Dark Period
The timing of when to start putting your poinsettia in the dark is crucial. You should begin the dark treatment around late September to early October. The exact timing depends on when you want your plant to bloom for the holidays. If you aim for your poinsettia to bloom by Christmas, the dark period should begin around September 25 to October 1.
This gives the plant the required 8 to 10 weeks of long nights to trigger the blooming process, so that by late November or early December, your poinsettia will begin to show its colorful bracts, ready for the festive season.
How to Provide Darkness for Your Poinsettia
To encourage blooming, your poinsettia needs to be placed in complete darkness for 12 to 14 hours each night. This process is called photoperiod manipulation. Here’s how to do it:
- Find a Dark Spot: The best way to ensure complete darkness is to place your poinsettia in a room with no light pollution or use a dark box or cloth to cover the plant. A closet, dark room, or cupboard can work well.
- Nighttime Darkness: Every evening, from approximately 5:00 p.m. to 7:00 a.m., the plant needs to be kept in complete darkness. Be sure that no light—whether from lamps, streetlights, or room windows—penetrates the space during this time.
- Daytime Light: During the day, place your poinsettia in a bright location with indirect sunlight. It doesn’t need as much light as typical houseplants, but it should still receive 6 hours of indirect sunlight each day.
How Long to Continue the Dark Treatment
The dark period should continue for about 8 weeks to achieve the desired blooming effect. By the end of this period, the plant will begin forming its buds, and the vibrant bracts will start to appear. You can stop the dark treatment after 8 weeks, and you’ll notice the first signs of blooming within a few weeks after that.
- Monitor Growth: After the dark period, your poinsettia will begin to flower. Once the bracts start to develop and you see them turning their vibrant colors, you can stop the nightly dark treatments and let the plant enjoy normal light.
Things to Keep in Mind
Consistency is Key: Make sure to keep the dark period consistent every night for the full 8 weeks. Even a single interruption, like light exposure during the dark period, can confuse the plant and delay blooming.
- Temperature: Keep your poinsettia in a temperature range of 65-75°F (18-24°C) during this period. Avoid exposing it to cold drafts or temperatures below 50°F (10°C), as it can stress the plant.
- Watering: During the dark period, continue to care for your poinsettia by watering it when the soil feels dry, but avoid overwatering. The plant may need less water as it enters the resting phase before blooming.
