Petunias are picky about the weather. If their leaves get wet and the nights are cool, they do get a leaf blight. They also stop blooming if heavy rains hit. If the weather is hot and the soil dries out, petunias will stop blooming and go limp. The best way to grow these annuals is with a drip system that waters the roots and not the leaves, or in a container using good potting soil and fertilizer. I have had good luck with Osmocote potting soil as the fertilizer is already mixed into the soil. You can pinch back your leggy petunias now shortening them to six inches. Fertilize and water and see if the new growth comes back healthy. If not, just rip them out and plant fibrous begonias instead. They rarely have problems and bloom in sun or shade. Keep growing, Marianne Binetti