Hydrangeas, known for their showy flowerheads, are some of the most popular flowering shrubs to plant as accent plants or for foundation plantings. The flowerheads, in shades of pink, blue or purple, add refreshing summer color to the landscape. Common hydrangea types are oakleaf, panicle, macrophylla and serrata. Some compact hydrangea varieties are suitable for growing in containers. When buying hydrangea bushes for sale, some factors to consider are their hardiness zone, sunlight requirements, mature height and spread, and flower color. Note that some hydrangea varieties have flower color that is dependent on soil pH. The flowers become bluer in acidic soils and pinker in alkaline soils.