Pakistan Gardening Forum

What happen to my zennias. [/URL]

Not sure, but I think this is heat stress symptom or over watering.

I think you sprinkle water over the plant hence making it wet.Always water Zinnias from the base so not making them wet.It also seems you water in mid of the day when its too hot.Either water in early morning or in late hours after evening.Sprinkling water may cause powdery mildew, Downy mildew & in mid of the day watering specially sprinkling may cause burns.
Always pinch pinch out the first flower bud to induce vigor.Before planting Zinnias apply old cow manure but not too much as its very hot when we plant out Zinnias.