Like other Endless Summer flowers, Endless Summer hydrangeas bloom multiple times throughout the summer season. Like other types of hydrangeas, all varieties of Endless Summer hydrangeas are susceptible to infestations that cause brown spots to form on the leaves. According to The United States National Arboretum, these spots are rarely fatal to a hydrangea, but they are unsightly. A few organisms can cause these spots, and they can be difficult to get rid of once they have developed.
Plant shading plants around the Endless Summer hydrangea bush. Hydrangeas grown in the sun develop brown spots more often than those that do not have direct sunlight, according to the U.S. National Arboretum. If you cannot plant any new plants in the area where the Endless Summer hydrangea bush is located, dig the hydrangea bush up and transplant it to a new location in your yard that gets more shade throughout the day.
Remove spotted leaves from the Endless Summer hydrangea plant as they form. Once a leaf shows signs of spotting, the organisms may spread to other leaves on the plant. Also, pick up any leaves that fall off the hydrangea plant and dispose of them away from the rest of your plants. The fallen leaves can still infest the rest of the bush.
Limit watering of the plant. According to the Alabama Cooperative Extension, the organisms that cause brown spots on Endless Summer hydrangeas cannot endure long periods of drought, so holding back water from the Endless Summer hydrangea for a few days can help stop the spread of brown spots. Limiting water may also slow the formation of new blooms on your Endless Summer hydrangea.