I'm hoping some more experienced gardeners can help me save my thyme plant. It was growing outside in a wider, shallower pot during the summer (I started it from seed) and doing really well. I live in Pittsburgh and the cold weather means I have to bring my herbs inside, which I did maybe 6 weeks ago. I divided the thyme and transplanted it into two other pots that I had because the original pot has to stay outside. Both seemed to be doing well under my grow light on top of the fridge with a small fan to circulate the air. I gave one of the plants away to spread the joy of fresh thyme during cold weather. Having thyme at hand during the winter is fantastic and I really hope I can save this plant with your help.
About a week ago the thyme started getting a bit, well, crispy on one side. A significant portion of it has now dried up and it seems to be spreading across the plant. You can see the progression in the photos below. The thyme is in a plastic pot (I didn't have any terra cotta handy) but it's so hot and dry in my apartment that even this pot dries out every 4 days or so. I usually wait another day before watering to try to avoid overwatering. I sprayed with neem oil a few days ago thinking that I saw some small white specks on the leaves and stems but it doesn't seem to have changed much so maybe it was just dust that I saw. I fertilize with a small amount of liquid fertilizer (1/4 tsp) about once a month.
Does anyone have any suggestions? My rosemary loves its spot next to a window near the radiator and the mint seems to be doing well under the growlight. It's just the thyme that has suddenly taken a turn for the worst!