Give Ruby Blossom rich soil plus consistent moisture in a soil that drains. It may require extra watering, but avoid standing water. Grow it in full shade or afternoon shade in the deep south (zones 8 and 9), not only for the foliage, but so the flowers don't get sun scald. Full sun is okay farther north. For flowering in cold climates, situate it in a warm sheltered location. During the ups and downs of spring temps here in Zone 8a - we cover to protect flower buds.
The flower color is not as you described, it's paler. Yes, I've come to the conclusion that Hydrangeas don't like to have their flower color profiled and clinically categorized like we humans try to do to everyone and everything. Please keep in mind that flower color varies widly and wildly depending on soil pH and the amount of aluminum actually in your soil, the amount of time aluminum has been availalbe to the plant (did you add Al only last month?), the unique propensity of how each cultivar reacts to Al, and if the flower heads get a touch of sunshine as they age.
The flower color is not as you described, it seems darker to me. Same issues as when it's paler; say after me, "a-lum-i-num-a-vail-a-bil-i-ty plus time plus cultivar plus a touch of sunshine."
This is science for sure, but also a whole lot of art. Enjoy the outcome Mother Nature deals!