Hydrangeas come in many sizes and forms. The two most well-known types are mophead, the old-fashioned large flower with a rounded flower head, and lacecap, in which the small fertile flowers are surrounded by large, colorful flowers. With some varieties, flower color is determined by the soil pH, with acidity causing blue flowers and alkalinity resulting in pink flowers. Other varieties are consistently blue, pink or white. Oakleaf hydrangeas (H. quercifolia) have elongated clusters of white flowers, large lobed leaves and, frequently, bold autumn color. They all bloom for a long period in the late spring and summer with the flowers lasting a long time. Hydrangeas thrive on good soil, constant moisture and no afternoon sun.