|What would cause a Poinsettia plant to lose all its green leaves but keep the red ones.|
It has been cared for as instructed, water sunlight etc. Otherwise it seems to be healthy.
|Your plant is doing just what it's supposed to do. Prune the stems back to stubs about 4 inches high. Put the pot in a cool, shady area of the house and keep the soil ALMOST dry.|
When spring arrives and it's warm enough to put your houseplants outside repot your poinsettia into a pot slightly larger than the one in which it had been planted. Put it into the garden in a slightly shaded area, sinking the pot into the soil to help keep it from drying
out. As soon as the temperatures begin to cool down in the very early fall bring it back indoors.
Put it into a very sunny location until sometime in September or early October when you will place it in TOTAL darkness for 13-14 hours every night. This is REALLY important. When the bracts have colored again, bring the plant out into regular daytime light and average room temperatures.