into the soil. To decrease the pH of a sandy soil by 1 pH point, incorporate 1.2 ounces of ground sulfur per square yard. For all other soil types, incorporate 3.6 ounces of ground sulfur per square yard. What do bigleaf and serrata hydrangeas need to grow and flourish in your garden? They need a soil that is neither too heavy nor too light. In extremely heavy, poorly drained clay, the fibrous root system of hydrangeas can be prone to rot. On the other hand, hydrangeas in general need lots of water, so they will never flourish in sandy soil. Whatever your soil type, amending with lots of organic matter -- rotted cow manure, compost, or leaf mold -- will ensure the right soil environment for your hydrangeas. Hydrangeas will tolerate full sun quite well in cooler areas of the country, if kept well watered. In the northern extremes of their range (Zones 4b to 5), they in fact require sun in order to produce enough flower buds. In the South (Zones 7-10), plant them in at least partial shade. In all cases, try to avoid so-called "frost pockets", or low-lying areas that stay colder than their surroundings. Likewise, plant hydrangeas in a site where they are protected from prevailing winter winds. A large conifer at their backs can provide shade, windscreen, and mild soil acidification all at once. With their abundance of large leaves and huge flowers, hydrangeas transpire lots of water. Except in rainy, maritime climates, they will