Meyer Lemon Problem

We have several questions that should help us figure this out. First and formost: was the plant outside this summer? Many citrus drop their leaves when they come indoors after a summer outside and this is not always fatal. How much sun is your lemon getting now? (It needs full sun – south facing window.) What kind of soil was it in? How wet is your soil staying between waterings? Are you letting it dry out before you water again? Meyer lemons should dry out between waterings and should be watered only when the top inch of soil feels dry. A soilless mix is best, because it dries out more quickly than a soil-based mix. Garden soil is a big no-no. It stays wet too long and is not sterile. Check for spider mites and scale, both of which can be problems on citrus, especially indoors.