The Hydrangia Shamrock, 'Hydrangea macrophylla 'Shamrock', a Proven Winners selection, is a nice new variety of hydrangea that is delicate and more refined than other mophead hydrangias. Shamrock will begin to bloom in July with pink or blue flowers, depending on soil PH, and as the season goes along the flowers will deepen into a rich red or violet. Shamrock blooms for a long time and the plant is more compact than other varieties. Place this plant in moist, well drained soils.