I planted 9 wave petunias in a whiskey barrel. At first they did fine. Now the center plants are falling over and not standing tall. I feed them every week and water every day with about a gallon of water. What am I doing wrong? This is my first time of growing flowers and have enjoyed watching them grow. Thank you for your reply.
Sometimes petunias benefit from being cut back. They can get "leggy" with few leaves along the lower part of the stems and flowers only at the tip. It seems drastic but I would cut them back by 1/3. Make sure to have leaves remaining or the entire stem will die. Petunias don't require fertile soil and with as much water and fertilizer you are giving them, might be growing excessively. Follow the instructions on the fertilizer container. Water when the soil is dry: keeping the soil damp by frequent watering can cause root rot. Let the top 1 " of soil dry out between waterings. In hot, dry or windy weather daily may be necessary but check the soil first. Here is more information: https://www.gardeningknowhow.com/ornamental/flowers/petunia/petunia-container-care.htm