How to Make Last Year's Poinsettia Bloom This Winter

You really can keep your poinsettias from year to year. If you have kept your plant from last year, you know that it makes a very pretty houseplant with its green leaves and red-tinged stems. The trick now will be to get it to "flower" again at holiday time.

Poinsettias do not really bloom. The red "petals" are actually just leaves. Day length is the determining factor which makes the plant produce the red bracts. Commercially grown poinsettias live in completely controlled greenhouses where light and darkness as well as temperature and moisture are closely maintained and monitored. You can simulate the necessary conditions at home.

Getting your poinsettias to color at the right time is the goal. It takes some patience and a regular schedule, but there is nothing difficult about it. In the late summer, clean up your plant, perhaps repotting it if it needs it after a good summer's growth, and trim away any dead leaves. Fertilize it in mid-August.

Beginning in early September, be sure that your poinsettia receives plenty of bright sunlight. Poinsettias need this to store energy for the next phase.

In order to bloom, poinsettias require a controlled period of complete darkness at night and very bright light during the days. The darkness must be complete darkness; any light leaking in, even a tiny amount, will interrupt the cycle and add days to the period leading up to "flower" formation. It takes 11 - 12 weeks to bring the colored bracts to the plant, with 6 of those being in the controlled environment. Beginning by the first of October should give you late December color.

In October, begin the controlled light/dark schedule. Since the darkness must be complete, a seldom used closet is a good place to keep your plant. Set up the schedule for 12 hours of complete darkness, and then 12 hours of bright light. Set an alarm if you need to so you don't forget to move your poinsettia. After six weeks of this treatment, your poinsettia can remain in regular light conditions. During the next 5-6 weeks you should see red bracts emerging from the growing tips of the plant.

Keep your poinsettia watered normally during this entire period. The soil should be moist, not wet, and never allowed to dry out.

It's a good idea to post a little reminder sign on the closet door so it is not unintentionally opened.

Poinsettias like temperatures of around 65 degrees night time, and up to 75 degrees daytime, so average household temperatures are good for them.

The poinsettia pictured is a start I made from a plant that was broken in a storm. I'll fertilize it now and get it ready to force. I first learned the "light connection" from a tag that was on a purchased plant several years ago.

Source:
Personal experience