Did you check to see if the stems or branches on the sick side got crushed or damaged? Petunias are so delicate that just a little pressure can damage the stems and they don't recover. Maybe you need to cut it back a little more on that side.
If I could see it I might have a better idea. As Tiger said, at least it's perking up on one side already. That's a start!
(ocultar) ¡Juega una partida en tiempo real contra un adversario conectado! Tan sólo debeís seleccionar por defecto la acción "Mover y permanecer aquí" y ¡recargar la página con la tecla F5! (TeamBundy) (mostrar todos los consejos)