If you want long-lived, healthy roses with an excellent root system, watering deeply and fertilizing are the best route to follow.
When rainfall is scarce and my rosebeds become dry, I water deeply using old milk gallon containers. I’ve shared this tip before, but I’ve adapted it a bit since last posted. Roses can develop black-spot disease if their foliage becomes wet. In the past, I always managed to get my roses wet when I filled the gallon container through the narrow opening at the top. This year, I cut a hole large enough to slip my garden wand into. Since I don’t begin to add water until the end of the nozzle is in the milk carton, the rose leaves remain dry.
A small hole poked with an ice pick or a screwdriver in one corner of the milk carton bottom is all you need to get a good supply of water into the soil. Because the water flows slowly, instead of running off to the side, it sinks down into the earth where it reaches the roots of the rose bush. Rose bushes thrive on two gallons of water per week in dry weather.
I also use the gallon watering method when I feed the roses every two weeks. I scratch the dry, organic fertilizer into the soil with a hand cultivator, then place the gallon over the loosened dirt and give the rose one to two gallons of water to work the fertilizer down to the roots. With minimal effort I deeply water and fertilize my roses with this method.
This deep watering technique also works well for newly planted bushes and trees. Larger perennials also benefit from this type of deep watering.