How to make a poinsettia turn red - the trick is putting it in the dark, but you must get the timing right

When to put a poinsettia in the dark, according to experts

Row of vases of poinsettia on mamtlepiece
(Image credit: Future PLC)

Adorably nicknamed ‘the Christmas flower,’ the poinsettia and its red flowers have long been associated with the festive period. But what do you do if your poinsettia leaves have turned green? And how do you make poinsettia turn red again?

Poinsettias are fairly low maintenance. Even if you do everything you can to follow the poinsettia care tips to a tee, though, it’s still possible to run into complications with this plant. You might ask yourself why your poinsettia is dropping leaves, or you might wonder why they’re a completely different colour from what you thought. 

To help you make your poinsettia turn red in time for Christmas, we’ve consulted with plant experts to give you all of the tips and tricks you need to make your plant merry and bright again. 

How to make a poinsettia turn red

‘To make your poinsettia turn red and thrive, give it some 'me time' in the dark’, says Alex Biggart, florist at 123 Flowers. But what does that ‘me time’ involve? Well, there’s no use giving your poinsettia a face mask and your Netflix password. This is a simple step-by-step guide on how to make your poinsettia turn red again.

Red poinsettia plant in pot with christmas gifts

(Image credit: Power Sheds)

What you’ll need


1. Choose the right time

If you want to ensure that your poinsettia is looking its best on Christmas day, the ideal time to start this process is in October. And while it is possible to make your poinsettia turn red again if you start later than October, it may be that the colour won’t be as vibrant as you’d hope. 

2. Put your poinsettia in the dark

Steve Chilton, garden expert at LeisureBench, explains the next step. ‘Around early October time, poinsettia requires uninterrupted darkness for at least 14 hours a day. To do this, cover the plant with a light-proof material, such as a cardboard box or black plastic bag, every evening until the following morning.’ 

However, if you have an airing cupboard or dark room with blackout curtains, this could also work. The aim is to keep your poinsettia away from any kind of natural or artificial light, as you essentially want to reverse the process of photosynthesis to turn your poinsettia red again.

Alex says, ‘Poinsettia 'flowers' are actually modified leaves called bracts. Reducing exposure to sunlight stops the plants from producing chlorophyll, which gives them a green pigment. This, in turn, changes the bracts to the signature red colour.’

Headshot of gardening expert Steve Chilton
Steve Chilton

Steve is a passionate and knowledgeable garden expert with several years of experience within the field and has developed strong expertise for all things nature and plants. Steve is a keen educator and loves to share this knowledge with others. He strives to simplify complex garden practices and encourage eco-friendly gardening.

Festive hallway and staircase, period style staircase with bannisters, real fir tree foliage garland with red berries and fairy lights, art deco tiled floor, wooden bech with scarves and wellies, berry wreath, cupboard under stairs

(Image credit: Future PLC)

3. Bring it out during the day

After putting your poinsettia to bed for the evening, it’s important to bring it out during the day. Place it on a windowsill or in a sunny area of your house so it receives sufficient sunlight, and aim to keep the temperature between 15 to 24C. 

Row of vases of poinsettia on mamtlepiece

(Image credit: Future pLC/Polly Wreford)

4. Repeat the routine

You can then repeat this routine for the next few weeks, making sure you also maintain a regular watering and fertilising schedule to keep it as healthy as possible. 

Let the top inch of soil dry out between drinks and feed it some plant food every few weeks,’ Alex says. But make sure you don’t overwater it, as overwatering is one of the easiest ways to kill your poinsettia. 

The experts suggest continuing this routine until mid-November. 

5. Stop the darkness treatment

When mid-November comes around, Steve suggests stopping the darkness treatments, as the plant ‘should begin to show signs of producing red bracts within a few weeks.’ 

This step requires some patience, and it’s important to understand that turning your poinsettia red isn’t a quick fix. It’ll take a few weeks to see the results of the darkness treatment. So, all you can do is wait patiently and maintain a regular watering and fertilising schedule. 

poinsettia in house pot

(Image credit: Bloom & Wild)

6. Cut back any faded leaves

While this process is almost always successful in making your poinsettia turn red, that doesn’t mean that it’ll look like a perfect specimen when you’re finished. In fact, you may find that some of its leaves look a little worse for wear. Thankfully, you can give your poinsettia a little prune. 

‘Once the red colour appears again, you can get rid of any faded or yellowed leaves to enhance the plant's overall appearance,’ explains Steve. 

And while you may be worried that you’ve missed the boat on turning your poinsettia red, you’ve still got time. Steve finishes by stating, ‘You can do this later on in the year, but it's important to follow the same timeframe.’


When should I put my poinsettia in the dark?

Ideally, you should put your poinsettia in the dark in early October if you want to ensure bright red leaves over the Christmas period. The aim is to give your plant at least 14 hours of uninterrupted darkness every single night until mid-November, making sure to only give it sunlight during the daytime. 

How do you get the colour of a poinsettia?

To ensure a poinsettia has its famous red leaves, you need to reduce its exposure to sunlight and give it less of a chance to produce chlorophyll - the pigment that makes leaves green. So, if your poinsettia has lost its red colours, the best way to get it back is to give it at least 13 hours of complete darkness every single evening for a few weeks in the run-up to Christmas. It’s best to do this between October and mid-November. 

Why are my poinsettia leaves green and not red?

To put it simply, if your poinsettia leaves are green and not red, it has been exposed to too much sunlight. The good news is that this can be reversed by keeping your poinsettia in complete darkness overnight for a few weeks between October and November. Of course, you can do this at other points in the year, but this timeframe is best for those who want to ensure red leaves over the festive period. 

No need to throw your poinsettia away if the leaves are green. Just give it some ‘me time’ instead! 

Lauren Bradbury

Lauren Bradbury is a freelance writer and major homes enthusiast. She graduated with a Bachelor’s degree in English and Creative Writing from the University of Chichester in 2016, before dipping her toe into the world of content writing. After years of agency work, writing everything from real-life stories to holiday round-ups, she decided to take the plunge and become a full-time freelancer in the online magazine world. Since then, she has become a regular contributor for Real Homes and Ideal Home, and become even more obsessed with everything interior and garden related. As a result, she’s in the process of transforming her old Victorian terraced house into an eclectic and modern home that hits visitors with personality as soon as they walk through the door.