Gardenia leaves yellowing.

[keeper_of_stars]

I'm in zone 5 in Illinois and have a gardenina bush that is worrying me. My dad said to make to bring it in in the winter, so I did, but now the leaves are yellowing. It was doing fine in the garage in December, but not growing any new leaves or buds. Now that it's in my house it's growing new leaves and buds, but the leaves are yellow.

Any help would be much appreciated.