Question
my 4 year old grape-fruit thee (which I started from a seed) was doing just fine, bur lately the leafs are dropping off, even the jung ones, I've been feeding it citrus tree food during the spring and summer, but now that the cold weather is beginin I've put the tree indoors, but I think some thing is happing to it, the pot the tree is poted in is about 9 inch in diameter and about 12 inch in depth,I know this tree will not have fruit, but I'll still like to have it for its folliage. Any advice you could provide will be appriceated.

Answer
Marta,

Without knowing the entire history of this tree I believe the cause of the leaf drop is the move indoors.  

When the environment changes, either temp or light, around a plant a classic response is to drop its leaves.  This also happens if an outdoor plant is brought in and placed near a heat vent or a door that allows cold air in everytime the door is opened.  New leaves will develop that will be better adapted to life indoors.  

Good luck

Gary