I started tomato seedlings indoors and they've been growing under a grow light just fine for a while. But about last week or so, the leaves started to turn yellowish with purple undersides. After looking it up, I learned they might be nitrogen/phosphorous deficient. So i watered them twice last week with Shultz 10-15-10 liquid plant food (7 drops to a quart as the instructions said) but they still haven't gotten better. I haven't watered with the fertilizer since because I'm afraid it will only make things worse. One of the leaves is even starting to curl up. Help!
