How To Make Poinsettia Turn Red – Make A Poinsettia Rebloom
By: Nikki Tilley, Author of The Bulb-o-licious Garden
The life cycle of the poinsettia may seem a bit complicated, but this short-day plant must satisfy certain growing requirements in order to bloom.
Where Did the Poinsettia Come From?
In order to fully understand or appreciate this plant, it is helpful to take a look at where the poinsettia comes from. The poinsettia is native to Central America, near southern Mexico. It was introduced to the United States in 1828 and got its name from Joel Roberts Poinsett. Poinsett was the first U.S. Ambassador to Mexico with a passion for botany. Upon discovering this shrub, he became so enchanted with its bright, red blooms that he sent some to his South Carolina home to be propagated.
What Makes Poinsettias Turn Red?
Many people wonder what makes poinsettias turn red. It is actually the plant’s leaves that provide its color through a process called photoperiodism. This process, in response to certain amounts of light or lack thereof, turns the leaves from green to red (or pink, white, and other shade variations).
What most people mistake as flowers are in fact specialized leaves, or bracts. The small yellow flowers are found in the center of the leaf branches.
How to Make Poinsettia Turn Red
In order to get a poinsettia plant to turn red, you need to eliminate its light. Flower formation is actually triggered by periods of darkness. During the day, poinsettia plants require as much bright light as possible in order to absorb enough energy for color production.
At night, however, poinsettia plants must not receive any light for at least 12 hours. Therefore, it may be necessary to place plants in a dark closet or cover them with cardboard boxes.
Make a Poinsettia Rebloom
To coax a poinsettia plant to bloom again, it’s necessary to repeat the poinsettia life cycle. After the holidays and once blooming has ceased, limit the amount of watering so the plant can go dormant until spring.
Then, usually around March or April, regular watering can be resumed and fertilizing can begin. Prune back the plant to about 6 inches (15 cm.) from the top of the container and repot.
Poinsettia plants can be kept outdoors in a protected sunny area during summer, if desired. Pinch out the tips to promote branching of new growth until about the middle of August.
Once fall returns (and shorter days), reduce the amount of fertilizer and bring outdoor plants inside. Once again, limit watering in September/October and give the poinsettia bright daylight temperatures between 65-70 F. (16-21 C.) with total darkness at night with cooler temperatures of around 60 F. (15 C.). Once the flower bracts have developed definite color, you can reduce the amount of darkness and increase its water.
This article was last updated on
Read more about Poinsettia
Reblooming a Poinsettia the Laidback Way
The poinsettia (Euphorbia pulcherrima) you bought for Christmas last year is probably now a small green shrub… and will remain a small green shrub if you don’t do something about it.
And probably like this right now.
You see, the poinsettia is a short-day plant, that is to say, it only blooms when days are less than 12 hours long. So its flowering starts to be initiated starting about September 22 in the Northern Hemisphere… and usually actually begins to occur about two months later, well in time for Christmas.
It all sounds wonderful: as days get shorter, the poinsettia should simply bloom naturally, right? Well, that may work in the plant’s native Mexico, or in other tropical countries where it grows outdoors, but it won’t work in the average home.
You see, we light our homes at night, extending the number of hours of daylight to 16, 17, or 18 hours a day. Yet what the plant really requires is no light at all from the end of the afternoon until the following morning. Even a single ray of light at the wrong time and it may not bloom.
So what’s a gardener to do?
The Hard Way
When I first started gardening, I was told you had to put your poinsettia in a closed box or a closet at 4 pm each day and remove it daily, putting it back in the sunlight, at 8 am. And that does work… but what a job! It means you have to be home at the right time each day (forget job considerations, or taking a weekend trip), plus you have to remember to do it every single day, without fail (not my strength: I’m good on resolutions, but weak in followthrough). If you forget even once, the plant won’t bloom. I’d be surprised even one person in 10 gets their poinsettia to bloom that way, yet check out most websites and books: that’s still the usual advice!
The Laidback Way
Here’s how I get my poinsettias (note the plural: I have all kinds, in lots of different colors) to rebloom. It works every time and requires no daily effort.
Place the plant in a room that you don’t usually use at night, but that is at least moderately sunny during the day: a guest room, for example. Now unscrew all the light bulbs in the room. Next, place the poinsettia near the window. Since you removed the light bulbs, even if you enter the room in the evening and try to turn the light on by accident (forgetting that is temporarily forbidden), you simply can’t. Whatever you were looking for in that room, you’ll just have to search for in the dark or wait until daylight to retrieve. And because your poinsettia has had a daily regime of short days, it will necessarily bloom at Christmas.
You don’t have a room that is not used at night? Then place your poinsettia near a sunny window somewhere else indoors and set up a panel of some sort between it and the rest of the room. Even a “wall” of taller houseplants will do, as long as no artificial light reaches the poinsettia. And this will give you a beautifully blooming poinsettia with no extra effort.
Otherwise, continue your usual care through the fall, remembering especially to water when the soil is almost dry and adding a bit of fertilizer. There is no need for special temperatures or extra high humidity… and certainly don’t prune (you’d be cutting off future flowering stems).
Merry Christmas in advance!
About Laidback Gardener
Larry Hodgson is one of Canada’s best-known garden communicators. After studies at the University of Toronto and Laval University where he obtained his B.A. in modern languages in 1978, he succeeded in combining his language skills with his passion for gardening in a novel career as a garden writer and lecturer. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He is a regular contributor to and horticultural consultant for Fleurs, Plantes, Jardins garden magazine and has written for many other garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening, Rebecca’s Garden and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 50 other titles in English and French. He can be seen in Quebec on French-language television and was notably a regular collaborator for 7 years on the TV shows Fleurs et Jardins and Salut Bonjour Weekend. He is the President of the Garden Writers Association Foundation and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. An avid proponent of garden tourism, he has lead garden tours throughout Canada and to the gardens of over 30 countries over the last 30 years. He presently resides in Quebec City, Quebec.
Should You Keep or Toss Your Poinsettia?
There is no need to toss your poinsettia after the holidays. If you want to try your hand at reblooming it in time for next year’s holidays, then follow the below schedule. To keep it simple, we have linked particular holidays with important care steps.
New Year’s Day: Continue watering as you have been. Don’t fertilize if the plant is in bloom. When it is no longer blooming, begin to fertilize at half-strength weekly.
Valentine’s Day: Snip the stems to about 5-6 inches. Look for bugs and if present, apply a safe homemade insecticide solution of 1 tablespoon of dish soap to 1 gallon of water put into a spray bottle.
St. Patrick’s Day: Prune dead and faded leaves from the plant. Add some fresh soil and keep plant in a sunny location.
Memorial Day: Cut new growth to get stems down to 5 inches to promote branching. Repot into a slightly bigger container.
Father’s Day: The plant can be moved outside into a partially shaded area for the rest of the summer.
Fourth of July : Pinch about 1 inch of new growth from the stems and continue to water and fertilize.
Labor Day: Bring the poinsettia indoors and return to a location that gets plenty of sun for at least 6 hours a day.
Autumn Equinox: Around September 21st, the plant needs to be placed in complete uninterrupted darkness for a minimum of 14 hours each night. A dark closet or under a cardboard box are good ways to achieve this. During the day, keep the plant in a sunny location and maintain watering schedule.
Thanksgiving: Time to stop the darkness treatment. Put your poinsettia in a bright, well-lit area so it receives at least six hours of direct light. Water when soil is dry and stop fertilizing.
Christmas: Enjoy your beautiful, newly bloomed poinsettia and then prepare to start the cycle all over again!
If your plant didn’t bloom, that’s okay. Getting a poinsettia to rebloom can take some practice. If you think it’s just too much work, that’s okay too! You can feel good knowing you’re supporting your local Anchorage florist by picking up a new poinsettia every year to enjoy for the holiday season.
Basic Care (January-September)
After Christmas, keep your poinsettia indoors and in a spot where it receives bright light, watering it regularly in a pot with good drainage to keep the soil moist.
When spring arrives, prune the flowering stems back 4 to 6 inches. This should promote new growth. In May, repot the poinsettia into a larger vessel, and place the plant in a sunny window. Water it when the soil becomes dry.
When June arrives and the possibility of frost is past, it's time to move the poinsettia outside. Place it in a shady spot and both water and fertilize it regularly.
When evening temperatures begin to drop in August or September, move the plant indoors and keep the soil moist.
Since they are tropical plants, poinsettias need lots of bright light, warm temperatures, and humidity to survive. When your plant is in bloom, maintain the below conditions for optimal growth.
Light: Poinsettias desire at least 6 hours of natural bright, indirect light every day. Choose a bright window free of cold drafts.
Temperature: Poinsettias like temperatures that fall between 65 and 75 F. If they are exposed to cold temperatures for too long, they will likely drop leaves..
Watering: Water only when the top soil feels dry, and make sure the water can drain thoroughly. Avoid letting the plant sit in water. Mist regularly to increase humidity.
Nutrients: Do not fertilize your plant while it is blooming. Feeding the plant will come later.
4 Keys To Keep Poinsettias Blooming All Through The Holiday Season
Proper watering is the most important of all! In fact, too little, or too much water, is usually the culprit when poinsettias fail.
And more times than not, it is too much watering that is more of a problem. Over-watering plants will result in soggy roots. And soggy roots can rot plants quickly.
Water plants when the soil first becomes dry to the touch. This allows the roots to keep from becoming saturated and soggy. But allows enough water to keep the poinsettias blooming longer.
If your plant is wrapped, be sure to create a few holes in the bottom to allow for drainage.
One more note on watering. If your plant is wrapped comes wrapped in a shiny foil cover, be sure to poke a few holes in the bottom and loosen the wrap.
This will allow the plant to drain from the bottom, and keep roots healthy. Remember, soggy roots = a struggling plant.
#2 Proper Room Temperature
Rooms that are too hot, too cold, or have wild swings of temperatures will lead to early bloom failure.
Poinsettias are a tropical plant, so they need both moisture and warmth, but not so warm that they bloom too fast.
To keep the bracts blooming at their best and. longest, a room temperature of 65 and 75 degrees Fahrenheit is ideal
Be careful of sitting poinsettias near a working fireplace. The dry heat can dry them out quickly, and lead to early bloom failure.
#3 Avoiding Draft
In addition to providing a consistent temperature, avoid placing poinsettias near drafty locations.
Keep plants away from heating vents, cold air returns, and at a safe distance from exterior opening doors. These short burst of cold drafts can shorten bloom times as well.
And that brings us to our last tip, proper lighting. To keep poinsettias blooming best, they do require a bit of light. Funny for a plant that needs to be in the dark to force the bracts to bloom!
Plants do not require direct sunlight, but a well-lit room will extend bract blooms for a few weeks.
After Christmas Care…
As with everything, all good things must eventually come to an end. And so it is with poinsettias and their blooms.
Poinsettias can be found in many colors other than red. White, salmon, and even apricot and cream are all just as stunning.
Usually, by late January to mid-February, most plants will begin to fade. But with a bit of care (See: Keeping Poinsettias Alive Before And After Christmas), they can be kept alive and thriving year after year.
Just another reason, they make a perfect holiday gift! (Affiliate link : 4 Pack Live, Foil Wrapped Poinsettias)
Here is to keeping your poinsettias blooming all through the holiday seasons!
This Is My Garden is a garden website created by gardeners, publishing two articles every week, 52 weeks a year. This article may contain affiliate links.