My poinsettia has lost several leaves. What is the problem?
Improper watering may be responsible for the leaf drop on the poinsettia. Over-watering will cause the lower leaves to turn yellow and drop. Plants that are allowed to get too dry will wilt and also drop leaves.
The water needs of a poinsettia can be determined with your finger. Check the potting soil daily. When the soil becomes dry to the touch, water the plant until water begins to flow out the bottom of the pot. The pots of most poinsettias are set inside decorative pot covers. When watering these plants, carefully remove the poinsettia from the pot covering, water the plant in the sink, then drop the poinsettia back into its pot cover.
Also, make sure the poinsettia is not located near a heat source or cold draft. Warm, dry air blowing across the plant from a furnace register or rapid temperature fluctuations (such as near a door) can also cause leaf drop.