Pink Diamond Hydrangea Hydrangea paniculata ‘Pink Diamond’ is an upright rounded Hydrangea with incredibly large flowers. The panicles open in late summer with valuable shades of color. It is first a cream color which gradually turns a rich shade of pink. The panicles are held upright and this large upright habit makes a good background or it can easily be trained as a small tree. It produces both sterile and fertile flowers. This a rugged reliable plant and is considered the most cold hardy of this clan. Cut blossoms are suitable for drying or prune off in late winter or early spring. Pink Diamond thrives in moist acidic well drained soils. This deciduous plant prefers sun or part shade in dry climates.