Most gardeners and growers think of poinsettias as a tricky plant to grow. This is because poinsettias are very sensitive to temperature and light variations. If the proper conditions are not met, the blooms will not form properly or wilt prematurely.

If you have a large greenhouse full of poinsettias growing and reflowering can be tricky. However, if you only have a few plants in your home it is easy.

Fortunately, there is plenty of information available on how to control these conditions properly.

The main conditions for growing poinsettias:

• Night temperatures above 50 F.
• Daytime temperatures below 70 F.
• A period of uninterrupted long, dark nights for about 2 months in the fall.

The ideal is to have a temperature of about 69 F all the time.

This is true of growing new plants or to get a plant to reflower in subsequent years.

How to make poinsettias flower or reflower:

• Light your poinsettia plants with grow lights until 2 a.m. until Sept. 25. Then cover with a black cloth from 5 p.m. until 8 a.m. until Oct. 15, followed with natural day lengths.
• Keep the temperature at 69F all the time.

This animation shows a poinsettia during the time it needs long dark nights to bloom for the first time. The same process works for subsequent reflowerings as well.

For more information about growing poinsettias:

• University of New Hampshire Poinsettia Information
• University of Florida Floriculture Poinsettia Page
• North Carolina State University Poinsettia Diagnostic Key
• The Texas Poinsettia Producers Guide

From Wikipedia, the free encyclopedia

In areas outside its natural environment it is commonly grown as an indoor plant where it prefers good morning sun then shade in the hotter part of the day. However they are widely grown and very popular in subtropical climates such as Sydney, Australia.

As this is a subtropical plant, it will likely perish if the nighttime temperature falls below 10 C (50 F) so is not suitable for planting in the ground in milder climates. Likewise daytime temperatures in excess of 21 C (70 F) tend to shorten the lifespan of the plant.

The Poinsettia can be difficult to induce to reflower after the initial display when purchased. The plant requires a period of uninterrupted long, dark nights for around two months in autumn in order to develop flowers. Incidental light at night during this time will hamper flower production.