Indoors tomato plant dying
I need some help.
I have a potted tomato plant that my girlfriend gave me last summer.
It was growing like crazy while I had it outside over the summer, had lots of blossoms, and I got a few tomatoes off it. I didn't move it inside until mid November because the weather was so nice. I got a couple more tomatoes off it after I moved it inside, and since about mid december it seems like it has been going steadily downhill. There were two actual plants in the pot, one of them died completely, the other (larger) one is visibly smaller than it was, quite a few leaves have turned brown and it just doesn't look good. I've seen no sign of any new growth or new buds.
I checked it out awhile back and it looked like it had powdery mildew, so I sprayed it a couple times with an herbicide, and it looks like most of the die-off has stopped but the plant just does not seem to be recovering.
Someone over in the fruits & orchards forum told me that it may be dying because "its time is up," and that I may be better starting from seed. However, this was given to me as a small albeit established plant and I had to wait almost all summer to get tomatoes off the thing as it was. Also, my girlfriend and her mother have potted tomato plants in their house that seem to weather the winter just fine and continue to produce tomatoes.