It is possible to keep your poinsettia alive into the Spring season when it can flower again for Christmas holidays the next year.
Of course, flower is the wrong word when dealing with poinsettias (Euphorbia pulcherrima, from the spurge plant family). They don’t have flower petals. Those red leaves are called bracts. The red leaves are just more leaves on the planet but they turn red as they grow from the top. The actual ‘flower’ is that knobby looking part in the centre of the plant. This is why poinsettias are propagated through grafting in commercial nurseries.
I’ve never tried growing one from seed either. I just do my best to keep my live plants going from year to year. I did have one which I kept for several years. It finally caught a white fungus during one of my moves from place to place. It couldn’t be saved that year.
The plant needs 12 hours of daylight followed by 12 hours of darkness in order to bloom – get the leaves to turn red. With some fussing, you can induce your poinsettia to bloom red again after the holiday season when the leaves usually begin to drop off and leave you with a pretty bare and barren looking plant.
How to Get Your Poinsettia to Grow Again
Prune the plant. Take off the red leaves, if there are any left. After the last of the frost is gone from outside, take it out for some fresh air. Don’t rush to get it out there. The poinsettia is not hardy for being out in the northern climate. They are native to Central America and Mexico.
You can leave the poinsettia outside all Summer. It will grow and look much healthier than it has since Christmas. Bring the poinsettia indoors in the Autumn. It really does not want to catch a chill outside. Bring it in before the first frost. Place the poinsettia in a room which you can give it darkness (complete and uninterrupted) after sunset. The plant needs those long, dark periods for at least two months if you want to get the red leaves developing in time for Christmas. Any light during this stage will set it back.
If you only have dim light, not full dark, try putting a cardboard box over the poinsettia for those 12 hours of full dark it needs. Another idea, put a tomato cage in the plant pot and cover it with a cloth/ fabric tablecloth to block out the light. Don’t use plastic, or anything else which will cut off the air as well as the light. Don’t forget to uncover the plant at dawn so it can also get the full 12 hours of light it needs. We tend to have longer nights than days in the Autumn so it will need all the daylight you can give it too, the balance of light and darkness.
Keep the poinsettia on the dry side when it comes to watering. Set the pot on a few pebbles, marbles, beads, something which will make sure it is getting good drainage rather than holding excess water inside the pot. I also pot them with a few rocks at the bottom of the pot if I give them a new container, other than the one they came in from the store. The poinsettia likes moist soil but it does not like to be sitting in water or have water poured over it. The best thing is to let it be just a bit dry and then give it a soak in a bucket (or some other container) of water. Then take it out to drain out any extra water before you put it back where you have it growing.