Several houseplants that were brought indoors in fall are dropping leaves. Why?

Question:

Several houseplants that were brought indoors in fall are dropping leaves. Why?

Answer:

When plants are brought indoors in fall they often drop leaves.  Environmental conditions indoors are less favorable than those outdoors.  The less favorable growing conditions are stressful to plants.  Plants respond to this stress by dropping leaves.  It usually takes plants 1 to 2 months to adjust to the indoor environment when brought indoors in fall.  Leaf drop may occur during this 1 to 2 month period. 

Plants are usually able to adjust to their indoor environment fairly quickly if they receive good, consistent care.  Poor or inconsistent care will prolong the adjustment period.