How to Get Poinsettias Ready for Christmas: A Complete Guide

Poinsettias are synonymous with the holiday season, their vibrant red bracts adding warmth and cheer to homes and offices alike. But if you want your poinsettias to bloom just in time for Christmas, the process starts long before December. Preparing these plants to produce their signature red (or white, pink, or variegated) bracts requires special care, especially when it comes to controlling their light exposure. This guide will walk you through how to prepare poinsettias for Christmas, including the steps needed to ensure they bloom with bright, colorful bracts just in time for the festive season.

Understanding Poinsettia Blooming

Poinsettias (Euphorbia pulcherrima) are native to Mexico, where they naturally bloom in winter. The bright colors we associate with poinsettia flowers are actually bracts, or modified leaves, that surround the true flowers, which are small and yellow. These bracts turn color in response to changes in light exposure—a process called photoperiodism. Learn more about poinsettia care from the University of Illinois Extension.

To get poinsettias to bloom and show off their red bracts, they need periods of uninterrupted darkness for about 8 to 10 weeks before Christmas. Typically, this process should begin in late September or early October to ensure blooming by December.

Why Poinsettias Need Darkness

In their native habitat, poinsettias naturally experience shorter days and longer nights as winter approaches. This decrease in daylight triggers the plant to begin developing its colorful bracts. When grown as houseplants, they need similar conditions to start blooming. If poinsettias are exposed to too much light—especially artificial light from lamps or streetlights—they won’t produce the red bracts that make them so popular during the holidays.

To replicate these natural conditions, poinsettias must receive 14 to 16 hours of complete darkness each night, coupled with adequate light during the day. Let’s explore the various methods you can use to ensure your poinsettia gets the darkness it needs.

Methods for Providing Darkness

1. Using a Dark Closet

One of the easiest ways to ensure your poinsettia gets the required darkness is to place it in a closet for 14 to 16 hours each night. This method works well because it blocks out all light and is simple to implement.

How to Do It: At around 5 p.m., place your poinsettia in a dark closet and leave it there until 8 a.m. the next morning. Be sure the closet is dark and cool (about 60°F is ideal) to mimic nighttime conditions.
Potential Issues: Be cautious with closets that may trap too much heat, or where air circulation is poor, as this could stress the plant.

2. Covering with a Paper Bag

If you don’t have a suitable closet space, using a large paper bag to cover your poinsettia is another effective method. A simple brown paper grocery bag will work perfectly, as long as it blocks all light.

How to Do It: Place the bag over the plant every evening and remove it in the morning. The advantage of this method is that it doesn’t require moving the plant, which reduces the risk of disturbing its root system.
Pro Tip: Make sure the bag is large enough to cover the entire plant and not too tight to allow for some air circulation. If the leaves start to yellow or wilt, check for any issues related to heat or moisture retention.

3. Creating a Light-Blocking Box

Another option for ensuring your poinsettia gets total darkness is to use a light-blocking box. You can create a custom box by using a cardboard box and lining it with black material or heavy-duty plastic to make it light-proof.

How to Do It: Place the poinsettia inside the box for the required 14 to 16 hours of darkness. Ensure that the box is sealed enough to block out all light but still allows some airflow to prevent overheating or moisture buildup. This method works well for plants in larger pots.
Watch Out For: Make sure the plant doesn’t receive any light leaks through small gaps in the box, as even a small amount of light can disrupt the blooming process.

4. Placing It in an Unused Room

If you have an unused room or space that remains naturally dark in the evenings, you can simply place your poinsettia there at night. This is a convenient option for those who have the space and want to avoid the hassle of moving the plant or covering it up.

How to Do It: Move the poinsettia into the room at sunset and bring it back into a lighted room in the morning. Keep in mind that if the room has windows or receives ambient light from outside, you may still need to cover the plant or the windows to ensure complete darkness.
Advantages: This method allows the plant to stay in one location for an extended period without being disturbed.

Daytime Care for Poinsettias

While darkness is crucial to encourage blooming, poinsettias also need sufficient light during the day. For the best results, place your poinsettia in a bright room with plenty of indirect sunlight. Ideally, the plant should receive 6 to 8 hours of natural light each day.

Additional Tips for Poinsettia Care During the Blooming Period

1. Maintain Proper Temperatures

Poinsettias prefer temperatures between 60°F and 70°F. Avoid placing them near drafts, heaters, or cold windows, as sudden temperature fluctuations can cause the leaves to drop. Keeping the temperature consistent is key to ensuring your poinsettia stays healthy and vibrant throughout the holiday season.

2. Watering

Poinsettias do not like to sit in water, so it’s essential to water them only when the soil feels dry to the touch. When watering, soak the soil thoroughly, but allow any excess water to drain out. Make sure not to let the pot sit in standing water, as this can lead to root rot. During the fall and winter, when the plant is in its bloom cycle, you might need to reduce watering slightly compared to the growing season.

3. Humidity

Poinsettias prefer moderate humidity levels, so if your home tends to be very dry during the winter months, you might need to increase the humidity around the plant. You can do this by placing a humidity tray (a shallow tray filled with pebbles and water) under the pot or by using a room humidifier.

4. Fertilizing

During the blooming preparation phase, poinsettias typically do not require much fertilization. However, once the blooming process is well underway and the bracts have started to turn color, you can resume a light feeding schedule, using a balanced houseplant fertilizer every 3 to 4 weeks.

For more detailed advice on plant care, visit our Plant Care Guide at Gardening Fast and Slow to keep your poinsettias and other plants healthy all year round.

Aftercare for Poinsettias: Keeping Them Healthy Through Christmas

Once your poinsettia begins blooming and the bracts change color, you can stop the daily dark treatment. At this point, the plant will only need regular care to keep it looking its best until Christmas and beyond.

Light: Continue to provide plenty of indirect sunlight during the day.
Water: Maintain a consistent watering schedule, but be careful not to overwater.
Display: Poinsettias make great holiday decorations. Place them around your home in festive arrangements, but avoid placing them too close to heating vents or cold drafts.

Post-Holiday Care

Many people treat poinsettias as disposable holiday plants, discarding them after Christmas. However, with proper care, poinsettias can be kept year-round and even rebloom the following holiday season.

If you wish to keep your poinsettia after the holidays:

Cut the plant back in early spring to encourage new growth.
Repot it in fresh soil, and continue to water and fertilize throughout the growing season.
In late summer, start preparing it for its next bloom by repeating the darkness process in the fall.

Conclusion

With a little effort and the right conditions, you can ensure your poinsettias are ready to shine during the holiday season. By providing them with the necessary light and dark cycles, proper care, and attention, you’ll have bright and festive poinsettias in time for Christmas. Whether you choose to place them in a closet, cover them with a paper bag, or use another method, the key is consistency in the dark-light cycle. And with a bit of extra care, your poinsettias can remain healthy and beautiful well beyond the holiday season.