Poinsettia - The Christmas Flower

This picture is of a Poinsettia that I have had for about four or five years. Not many people keep them for very long after Christmas but with very little care and attention they can be kept for years - just like any other houseplant.
Poinsettias (Euphorbia Pulcherrima) grow wild in Mexico and Central America so the conditions they are kept in need to be similar to their native climatic conditions. Having said that they are quite forgiving and adaptable as are most houseplants which is precisely why they can be grown as houseplants. In the wild they grow as a shrub up to ten feet in height.
The red "flowers" aren't flowers at all but bracts or modified leaves. The small, insignificant flowers can be seen in the centre of the red bracts. They are now bred in various colours including pink, white even yellow.
A sunny windowsill is an ideal position, avoiding draughts and direct heat from radiators etc. The compost needs to be kept moist but not wet and certainly not standing in water or allowed to dry out completely. The night time temperature should not be allowed to drop below 10 deg.C. In late Spring when the red leaves start to fade or drop off the plant can be pruned back and fed, watered and treated as any other houseplant. One other thing worth mentioning for those with sensitive skin is that the white sap can be irritating so best to avoid getting this on one's skin.
The trick to encouraging it to turn red again for the next Christmas lies in the hours of light and darkness it receives. Mine is kept in a room that is rarely used in the evenings and so receives no artificial light from inside or outside in the form of street lighting and this is the key. As the Autumn nights naturally lengthen from September onwards, this extra darkness is what makes the Poinsettia's red bracts form. If it is kept in a living room or any room that gets artificially lit in the evenings then it is very unlikely to turn red. A way around this is to place it in a dark bag or box every night for at least 12 hours but this would take a good memory and lots of dedication to achieve this.