How do I get my poinsettia that is in a pot to bloom by christmas?

Here is what I could find on the subject: If you have two or three you might be able to stagger the flowering to always have one out in bloom while the others are “in the dark.”

Before night temperatures fall below 55-60°F at night, bring the poinsettia indoors to a sunny location. Check for pests and diseases and place poinsettia in a south window.

Flowering is “photoperiodically” induced in the poinsettia. This means that flowers begin to form when the days are a certain length, or, more accurately, when the nights are long enough. The poinsettia is a short-day or long-night plant. Without long nights, this plant will continue to produce leaves and will grow but will never flower. You must make certain it receives no light from any source.

Very short periods of lighting at night may be enough to prevent or interfere with flowering. Even light from a street light can stop flowering. If the plant is to be grown in a room that is lighted nightly, cover it completely at dusk (5p.m.) every day with a heavy paper bag, a piece of opaque black cloth, other light-tight cover or place in a dark closet.

Flower initiation begins in late September and early October. Dark periods longer than 12 hours are necessary for flower set. Flowers mature in from 60 to 85 days depending on varieties, temperature and light intensity.

Because flower initiation depends upon the length of the dark period, your poinsettia must be kept completely dark from 5 p.m. to 8 a.m. The time to give this treatment is from the end of September until December 15.

Once you can see the flowers developing in the growing plants, I. e., when the floral bracts start to show definite color, it is not as important to continue giving the dark period, though it is advisable to continue until the bracts are almost fully expanded.

Temperatures should be no less than 55°F at night, but not more than 70°F. During the day give the poinsettia as much sunlight as possible.

Reduce the amount of fertilizer given after bringing the plant indoors. Growth is slower in the lower light intensity inside the house.

High night temperatures, coupled with low-light intensity, low nutrition, dry soil or improper photo period may delay maturity.