oregano plant died

[robneal17]

Hello everyone
I started a bunch of oregano plants from seeds at the start of the summer. some of them flourished, some did okay. I took a flourishing one, put it in a different pot and brought it to school with me. The leavers began turning brown so i repotted it, but the plant still slowly died. I put it out of it's misery today.

why did this happen? i see it happening on the other potted oregano plants too, just not as fast. Is it due to too much water? I notice the soil stays wet for longer in an indoor condition because I have standard lamps instead of sunlight which also gives radiant heat to evaporate water.

I also had a parsley plant spontaneously succumb to root rot yesterday, over the period of one, maybe two nighnts indoors. I'm definately thinking im overwatering given a standard potting soil mix with no provision for the lack of sun energy.

Thoughts?