An update from my side. All my plants have recovered well. No leaves drying, no brown borders nothing any more. Here is what all I did:
1. "Ploughed" and aired the soil in the pots
2. Added compost (vermicompost and cow manure) to the pot soil
3. Made four holes on each pot on the sides
I've been watering the plants once every 3 days for now (since its winters and there is no direct sun on the pots) and it has been going very well.
Thanks a million to everybody for their inputs. Now my miniature garden looks really pretty and smells beautiful with the blossoms!