Endless Summer Hydrangea

Endless Summer Hydrangea is a Hydrangea macrophylla that was discovered by Vern Black of Bailey Nurseries in 1983. Vern was impressed with the amount of bloom and hardiness of plant in a Zone 4 climate where H. macrophylla generally performs poorly as the buds set the previous year are typically killed in most winters.

In 1988, plants of Endless Summer were observed by Dr. Mike Dirr, who took cuttings back to the University of Georgia's Center for Applied Nursery Research for further testing. Dr. Dirr is quite impressed with Endless Summer, particularly because of its ability to consistently bloom on new wood. It was his encouragement that led Bailey Nurseries to take this plant quite seriously in terms of introduction. He currently has a number of studies in progress with Endless Summer that will help us further define its attributes and production.

Characteristics based on current results/experience:

• Endless Summer is a mop-head type with clear pink blooms in soils with poor aluminum uptake typically alkaline soils, and blue flowers in acidic soils with sufficient aluminum. Blue flowers can be achieved in alkaline soils by adding aluminum sulphate to the soil to change the soil PH. Flower size is 4 to 6 inches across under garden conditions, and up to 8" in diameter on vigorous container plants.
• The most unique characteristic of Endless Summer is its ability to bloom on new wood. If the new emerging growth is cut back to half, the amount of bloom is significantly increased. In addition, removal of spent blooms results in repeat bloom. If spent blooms are removed, one can have bloom from June until frost in Minnesota, and from June until November or frost in Georgia.
• Endless Summer has performed well in Zone 4, although it is not as stem hardy as Nikko Blue. Its ability to bloom on new growth has resulted in dependable bloom, thereby extending the range for successful bloom with H. macrophylla.
• Endless Summer has good foliage, medium to deep green with good substance, and is mildew resistant. In comparison to some cultivars, resistance is definitely better than Nikko Blue.
• Endless Summer appears to have potential as a potted plant as it has the ability to set flower buds on new growth without a cold treatment. Studies are currently underway by Dr. Neil Anderson at the University of Minnesota to more clearly define potted plant production.
• Mature plant size is 3 to 5 feet in width and height.