Do you throw out your Christmas Poinsettia plants each January? It isn't necessary, and purchasing new ones each year costs a lot of money. Also, they are not a short lived gift plant. Instead, they will last years and years if treated like a normal house plant. I have some that are years and years old. I also have some that are as young as three years old.
The red leaves will last until about May if the plant is kept in bright light. I love the look of Poinsettia plants and enjoy looking at their red leaves all winter and spring. When the days get longer in late spring/early summer, the red leaves will drop off and the plant will start to grow new stems. (You can transplant into a bigger pot at this time if you wish.) Since this is the time the plant will grow, it will need fertilizer through the end of September. Here is one of mine. I transplanted it into a new pot in May and it lives in my bathroom.
Here is another one. This one did not loose all of it's red leaves this summer. It is in the same pot from last year.
I want them to be red for Christmas this year. So, to turn these red myself, I will 'treat' them with a forced dark period. It is super easy to do! It takes approximately one minute per day. If you do some research on the internet, you will find that most articles will say you only need to treat them to a forced dark period for two weeks to get them to turn red. That may be true if you own a greenhouse with computerized light switches that allow you complete control over the light. When treating them in a home environment, my experience over the years is this treatment needs to continue for 60 days. However, since it only takes 1 minute per day, it is not a big effort at all.
So the first thing I do is move them to a room that will not be used at night. This is the hard part. Who wants to live in a house with rooms that are closed off at night? So, if like me, you don't really have a spot that meets that requirement, use a room that gets the least amount of use after the sun goes down. I put my plants in my guest bedroom.
Treatment takes 30 seconds at night and another 30 seconds in the morning. When the sun goes down, turn off all lights in the room and close the blinds. Shutting the blinds is necessary so the moon and/or streetlights do not shine on the plants all night. Then, as you exit the room, shut the door. This is also necessary to block the lights in the rest of the house from reaching the plants. If you need to go into that room and turn on the light later in the evening, so be it. Just be sure to turn off the light and shut the door when you leave. These 'interruptions' of light during the dark treatment is why it takes 60 days to turn the plants red in a home environment. If you can be really disciplined and completely block off a room that will not be used at night, you can reduce the number of days the plants needs the forced dark treatment.
I have noticed over the years, that the red Poinsettias are the easiest to turn. White, pink and other variations, don't do as well for me. If I want a Poinsettia plant that is another color, I will purchase a little one at Christmas time to enjoy that color. I still keep it for a few years and give it my forced dark treatment, but my results have been less then satisfactory in getting them to turn colors. Those plants I tend to eventually toss out.
When Christmas time come this year, consider keeping your Poinsettias as full time houseplants. Turning them red for the next year, is definitely doable! No special skills or equipment needed!
I will be sure to post updates as we get closer to Christmas so you can see the results!