One of my sunflower leaves turned yellow and dried since 2 days ago. The bottom leaves became crispy and the top leaves slightly curled. I did watering it daily so I am not too sure is it over or underwatered. I touched the soil on top and bottom it's dried so I assumed it lack of water. I tried gave it additional water and moved it under shade. The other sunflower had same problem yesterday. Most of the bottom leaves dried up within half day, although additional water slow down the problem but I can see the top leaves started to turn yellowish too.
It's flowering soon, how can I save it?