Gardening

http://en.wikipedia.org/wiki/Poinsettias

Cultivation

With care, the poinsettia can be induced to reflower after the initial display when purchased. The red blooms should be pruned, and the plant moved outdoors after the last frost. It should be returned indoors in the Fall, before the first frost, to a room which is not lighted after sunset. 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. When watering it is important to allow the plant to drain out any excess water. Having a poinsettia sit in water can do harm to the plant as it prefers moist soil to direct water.

In order to produce extra axillary buds that are necessary for plants containing multiple flowers, a phytoplasma infection – whose symptoms include the proliferation of axillary buds – is used.[