The most important thing for keeping your seasonal container looking lush and lovely is regular watering. Check the soil to determine if watering is needed, the top two inches can dry out without causing any harm, but it should start to feel damp. Your plants can often tell you that they need a drink just by looking at them. Wilting leaves and stems are a clear sign that things are too dry.
The size of a container and its location can have a major impact on how frequently it needs watering. Smaller containers dry out faster than large ones, and containers in direct sun will need more frequent watering than those in the shade. If potting soil gets too dry for too long, it can become difficult to soak up water, letting it all run out of the bottom of the container. If this happens, water slowly a few times through the day to help the potting soil soak up water and fill in the container edges to be sure it actually gets the water you are adding to the roots of your plants!