Answer: Daily watering is a bit much for petunias. They like a deep soaking, followed by a few days when the soil can dry out. If you keep the soil too moist you'll drive out the oxygen; roots need oxygen as well as moisture.
Roses are sun lovers - a minimum of 8 hours per day, and they like rich, moist soil. Prior to planting, amend the planting bed with organic matter, plant the roses, and then water them well. Make a watering well or basin beneath each plant. When you water (once or twice a week, depending upon weather), fill the basin, allow it to drain, then fill it a second time. If you apply a few inches of mulch over the top of the bed you'll moderate soil temperatures, help slow evaporation, and suppress weeds. Roses are heavy feeders so purchase some specially formulated rose food and feed in amounts and with the frequency listed on the label.
Best wishes with your garden!
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