Oakleaf hydrangea, or Hydrangea quercifolia, is a flowering shrub hardy to U.S. Department of Agriculture zones 5 through 9. This variety of hydrangea is native to many southern states. Large clusters of white flowers appear in midsummer, later changing to pink and finally to a deep red in the fall.
Difficulty: Moderately Easy
Test garden soil’s pH levels prior to planting. Test kits are available at many garden centers. Soil samples may also be taken to your local county extension office for testing. Oakleaf hydrangeas grow best in a soil pH between 5.5 and 6.6, according to North Carolina State University’s horticulture department.
Choose a planting site with moist soil. Oakleaf hydrangeas may not grow well in hot, dry areas of the garden. However, the planting site can be in sun or shade, because oakleaf hydrangeas thrive in both.
Plant these bushes approximately 5 feet apart. Oakleaf hydraingeas tend to grow outward as much as upward, reaching heights and widths of about 8 feet. Surround freshly planted hydrangeas with 3 inches of mulch to aid moisture retention and reduce competition from weeds.
Prune these bushes after the flowers have died or during the winter. Prune early in the winter to avoid negatively affecting the next season’s growth. Prune approximately 1/3 of growth for a fuller, more compact plant, notes North Carolina Cooperative Extension.
Apply approximately 1 oz. of nitrogen fertilizer annually to the soil surrounding the hydrangea.
Water often. Watering needs are at the root of this plant’s name. Hydra is the Greek word for water, and hydrangeas love water. This hydrangea’s roots should be kept moist but not soaking wet.
Oakleaf hydrangeas may be grown in the ground or in containers. Container plants have similar requirements for growth with the exception of soil. Hydrangeas grown in flowerpots do well in pine bark potting mixes, according to the United States National Arboretum.