It does not matter whether your flowers are inside or outside, they constantly need a little care.
This time of the year flowers need a lot of water. However, it is not good to water them with cold water. They could get a cold shock. It is better to water the plants with room temperature, stagnant water. The best is to refill the watering can after every watering. So the water is already stagnant for the next time. In addition, make sure you water the flowers only at their roots. The leaves should not get wet because the strong sun could burn them.
Many flowers are self-cleaning by dropping their dead blossoms. Nevertheless there are also some flowers which do not clean themselves. That is why you should pinch off withered blossoms with your thumb and finger. This allows the flower to build new blossoms.
If your flowers develop magnificently in a pot, sooner or later the flower pot might get too tight for them. In this case, you should either prune the flowers or replant them into a larger pot.