I have always grown roses for their large red berrylike fruit known as the hip. It forms in the wake of a fertilized flower. During World War II, the British discovered that rose hips contain more vitamin C per ounce than citrus. Their analysis also verified a host of other vitamins and minerals within its flesh that led to "rose hips" becoming a popular natural source of vitamin C.
In the self-sufficient home garden, there's a real purpose for the kinds of roses that make good fruit. The modern Flower Carpet and its contemporaries produce little or no fruit because they were bred to eliminate the need to prune off spent blossoms. The result was small raisin-sized hips that are impossible to use -- if and when they occur.
Old roses usually bloom just once a year in late spring with a massive show of color. These are better for gathering like a traditional crop, because they're all ripe at the same time. That gives you enough quantity to make your own rose-hip jelly. It's also enough to pick, prepare and dry to use later in winter to treat colds and flu with vitamin-rich medicinal rose-hip tea.