Oak leaf hydrangeas are a hydrangea variety that is native to North America. These large, showy shrubs are hardy from USDA zones 5 through 9 and will provide beauty and interest in a landscape during all seasons of the year. Plant an oak leaf hydrangea in a sunny or partly sunny location and ensure the soil drains exceptionally well to keep the roots from decaying.
Prepare a growing area for planting in the spring or in the autumn. Work the soil with the garden spade to loosen it and then add compost to the soil if the soil needs organic materials to enhance the drainage. Clay soils will especially benefit from adding compost when planting oak leaf hydrangeas.
Space the holes 8 to 10 feet apart to accommodate the mature growth of the oak leaf hydrangeas. Dig each hole at a depth that will place the hydrangea plants at the same depth as it was growing in the temporary container.
Remove each oak leaf hydrangea plant from its temporary container and loosen the roots along the sides of the root ball slightly with your hands. Place each hydrangea plant into a prepared hole and fill the soil in around the roots carefully.
Provide a generous watering for the oak leaf hydrangeas immediately after planting. Ensure the hydrangeas receive at least 1 inch of water each week, especially during the first two years of growth and during drought conditions.
Apply a 2-inch layer of shredded bark mulch around the base of each oak leaf hydrangea to conserve soil moisture and prevent weeds from growing.
Fertilize the oak leaf hydrangeas one or two times during the growing season. Sprinkle 1/8-cup of fertilizer around the soil of a small oak leaf hydrangea and up to 3 cups of fertilizer around the soil of an extremely large hydrangea. Work the fertilizer into the soil with a hand rake and water the hydrangeas generously after fertilizing. Do not fertilize the oak leaf hydrangeas after August to allow the plants to enter the dormancy period.
Prune the oak leaf hydrangea immediately after the shrub finishes blooming. Cut off the entire stems that just finished blooming. Examine the hydrangeas in the spring to find dead or damaged branches and remove these before new growth begins.