A saucer makes it easy to see when water has run through a pot. It also makes it easy to leave the roots above a pool of water long after the watering is finished.
Check the compost before watering. If the root area needs moisture, water the compost thoroughly and let the excess escape. Then empty water that has collected in the saucer or outer container.
Look below the dry surface
The top of a pot can dry before the rest of the root ball. Check more than the surface, particularly in a large container or cool weather. The opposite can happen too: water may run down a gap while part of a dry root ball remains difficult to wet.
A rose outside will not need the same attention every day of the season. Wind, heat, rain, root growth and pot material all change the rate of drying.
Keep watering decisions separate from feeding decisions. A dry plant needs appropriate watering; a wet plant does not become healthier because fertiliser has been added to the water around its roots.
Related reading: Rose Care: Sunlight, Watering, Feeding and Maintenance.