URGENT! growing mint indoors
I live in a country where finding fresh mint is incredibly difficult. Last week I happened to pass a vendor at the market who was selling potted mint! So I picked up 3 (two spearment, one peppermint). I live in an apartment and must grow them indoors.
They were lush and green when I first got them. Now they are starting to look a bit sickly, losing their dark green colour (now they are sort of pale green). I've been watering them 2-3 times per week. The soil feels sandy and seems to get dry quickly. Initially I put them on the windowsill, but then they started to droop; I have a very sunny apartment!! So now they get indirect light, further away from the window.
I don't want them to die! I'll probably never find mint again. Can you help me figure out what's going wrong? What do I need to give them?
p.s. I'd really like to re-pot them so that they can grow larger. But every time I've repotted something here in Korea, it dies. I think it's something to do with the very dense soil, which is probably made of compost. I've tried to put rocks in for drainage. Maybe I also need to mix some sand in? Admittedly I have no idea what I'm doing ;) I'm a complete newbie. Please help.