Sprinkle a half cup of Epsom salts on the surface of the soil (not touching the plants) around newly planted roses. It gives them deeper color, thicker petals, and stronger roots.
For a mid-summer pick-me-up, sprinkle any leftover tea leaves on the soil underneath each bush. The tannic acid in tea makes the soil slightly acidic, which roses just love. You can mulch with pine needles which will give the same result.