It is impossible to plant a rose either in a container or in the ground without damaging some of the root system. In a sense, this makes the root system inefficient to support the top growth.
The first thing a rose does is grow roots and then it starts sending more moisture to the top growth. During that period, the top growth will look stressed.
The easy way to determine if you need to water a container rose is to lift the side of the pot ... if it's not too large. If it feels "heavy" the soil in the pot is moist enough. Since roses don't like to grow in saturated soil, you water when the pot feels "light".
With some roses, depending on the type of container and depending on the rose, you will end up watering every day during the hottest part of the season because these are what I call "thirsty roses". With other roses and different types of containers, you may end up watering every other day or even every few days. By lifting the pot, you know when it's time to water.
