One of the most recognizable and popular flowering shrubs for sale, hydrangeas are known for their large flower heads in shades of pink, blue or purple. Hydrangea types include oakleaf, panicle, macrophylla and serrata. In the garden, hydrangeas can be planted as accent plants, foundation plantings and flowering hedges. Before buying hydrangea bushes, make sure they are suitable for your hardiness zone. Other factors to consider are how much sunlight they require. While some hydrangeas like full sun, others prefer more shade. Some hydrangea varieties have flower color that is dependent on soil pH. The flowers become bluer in acidic soils and pinker in alkaline soils. Some hydrangeas have stable flower colors that are not dependent on soil pH.