Curling, bending and wilting of basil leaves generally happen due to
1. Excess or too little water: How frequently do you water? Water only when it is necessary, i.e, when top 1 to 2 inch soil is dry. Though it depends on weather condition one can usually water once every four to seven days. And make sure the drain hole of your pot is not clogged. Also avoid wetting of leaf surface.
2. Sunlight: Basil is sun-loving plant which needs minimum six hours of sunlight per day. So place the pot in good sunlight area.
Hope this helps.
Posted by: Dr. Ravishankar Narayana
Posted: November 14, 2017