Hydrangeas conjure up images of an old-fashioned garden, with their delicate, lacy blooms of pink, blue, purple or white. These woody shrubs, native to Asia, come in many cultivars. Variegated hydrangeas have green leaves with white marbling or margins. Favorite variegated cultivars include Quadricolor, Maculata, Silver Variegated Mariesii and Light O' Day.
Plant your variegated hydrangea in a partly shady area with moist, well-drained soil. Too much shade can keep your hydrangea from flowering, according to the U.S. National Arboretum. Do not choose a dry, windy site. Excessive wind will cause the leaves to quickly dehydrate and the plant to wilt, according to the University of Rhode Island Landscape Horticulture Program.
Water weekly during the first season after planting your hydrangea. After that, water thoroughly only during dry spells. Apply 2 to 3 inches of mulch around the base of the plant and outward to its drip line to help retain moisture.
Cover your hydrangea, if needed, during late spring freezes to protect it from flower bud damage. You can use light blankets or sheets. Remove the covers once the temperature rises above freezing.
Change your plant's flower color by adjusting the pH. According to the National Arboretum, blue flowers will be produced in acidic soil (pH 5.5 and lower), and neutral to alkaline soils (pH 6.5 and higher) will produce pink flowers. If your soil's pH is between 5.5 and 6.5, the hydrangea will bloom purple or have a mix of blue and pink flowers on the same plant.
Prune about a third of the plant's oldest stems each winter to produce a fuller bush and remove cold damage. You also can prune to reduce the plant's height or to cut off dead flower heads.
According to the National Arboretum, bigleaf and oakleaf hydrangeas, which flower on the previous year's growth, should be pruned within a month after flowering has ended. Panicle and smooth hydrangeas flower on this year's growth, according to the National Arboretum, and can be pruned any time from late summer until early spring.
Treat powdery mildew by giving your plant more light and better air circulation. Either trim back trees that are blocking the sun and plants that are crowding the plant, or transplant your hydrangea to a new location.
If your hydrangea is suffering from root rot, the soil is not draining properly. Symptoms include plants that look wilted but don't recover after being watered. You can try to amend the existing soil or transplant your shrub.
Fertilize hydrangeas in early spring with a top dressing of complete granular fertilizer at the rate of 2 lbs. per 100 square feet, according to the University of Rhode Island.