Hydrangea Help

Identification

• Hydrangea varieties include bigleaf or French, oakleaf, peegee, smooth and climbing hydrangeas, as noted by the University of Georgia College of Agricultural and Environmental Sciences. The plants are native to Asia and the Americas and are commonly grown in the Southeastern United States. The flowers usually bloom in May, June or July and come in a variety of shapes, including round or cone-shaped flower clusters. Bigleaf hydrangeas, which are the most common type, grow in 4- to 12-foot tall shrubs.

Soil pH

• In acidic soils with pH levels between 5 and 5.5, flowers of some varieties will turn blue. In soils with pH levels of 6 or more, flowers will be pink. The color change is caused by aluminum availability and quantity, which varies based on pH levels. In acidic soils, aluminum is more available to plants, whereas high pH levels result in lower aluminum levels. Gardeners can change the color of the flowers by adding aluminum sulfate or hydrated lime to their garden soil.

Growing Practices

• Most hydrangea varieties are easy to grow and maintain in the right climate and soil conditions. The plants need well-drained soil with a large amount of organic matter. Although they do well with morning sun, they also require shade in the hottest parts of the day. Plant hydrangea transplants during the fall or early spring and apply an all-purpose fertilizer in March, May and July.

Common Problems

• Observe your hydrangeas for signs of weather-related damage, pest infestations and disease. The most common problem for most hydrangea gardeners is cold injury, which can prevent the flowers from blooming. Other common cultural problems include too much shade, excessive nitrogen levels and low soil fertility. Hydrangeas are particularly susceptible to a variety of diseases, such as leaf spot, powdery mildew. Insect pests include aphids, leaf tiers, rose chafers and red spiders, as noted by Clemson University Extension.