It's hard to beat the spectacular mophead hydrangea flowers for shadier locations of the summer garden, though the soil pH will often determine the color of the blooms. Blue Enchantress hydrangea has large blue flowers in acidic soil and more pinkish flowers in alkaline soil. Fast growing once the weather warms, this variety can eventually grow to five feet tall and wide. Pruning in late fall to late winter will keep the shrub itself more compact and not affect bloom production. Morning sun with afternoon shade or all-day dappled sun will result in plentiful flowers. Be sure to protect any mophead hydrangeas from the late afternoon sun to avoid sunburned leaves and burnt flowers.