Petunias may be wilting for several common reasons including improper watering (either under- or overwatering), root damage, temperature stress, nutrient deficiencies, pests, fungal diseases, or environmental factors like hot and dry weather. Overwatering can cause root rot, preventing water uptake and causing wilting, while underwatering leads to lack of moisture. Petunias also prefer well-draining soil, full sun, and may wilt if exposed to extreme heat or if planted next to plants like tomatoes that encourage fungal root diseases. Additionally, fungal diseases such as powdery mildew or root rot and pests like aphids can lead to wilting. Ethylene gas exposure, from decaying plant material or stress, can cause petunia flowers to wilt prematurely as well. Checking soil moisture, ensuring good drainage, providing adequate sunlight, and monitoring for pests or diseases can help prevent wilting.