Endless summer hydrangeas are ornamental flowering plants that bear flowers on both old and new wood. They are hardy to USDA zone 4, and they are valued for their ability to bloom even in cool climates. Flowers appear throughout spring and summer. The plants are easy to grow almost anywhere with proper care and maintenance. The flowers' color depends on the soil in which the plants are grown. Soil with an acidic pH will produce blue blossoms, while soil with a neutral or alkaline pH will produce pink blossoms.
Plant Endless Summer hydrangeas in early spring. Choose a planting location that receives morning sun and dappled afternoon shade. Provide at least six hours of sunlight per day in zones 4-5. In warmer climates, less sun is required. Make sure the area is protected from cold winds and the hot summer sun for the best results.
Water Endless Summer hydrangeas two to three times per week during spring, summer and fall to keep the soil consistently moist. Water immediately any time the leaves begin to droop, as this is a sign of inadequate moisture. Continue watering until the ground freezes in late fall and then cease until the ground warms in spring.
Apply a 4- to 6-inch layer of mulch to the base of Endless Summer hydrangea plants in fall to insulate them during winter. Replenish the mulch throughout fall and winter if it becomes visibly deteriorated. Remove the mulch in early spring after all danger of frost has passed.
Feed Endless Summer hydrangeas once per year in spring or early summer. Use a balanced slow-release fertilizer with an NPK or 10-30-10 or 10-40-10 to promote flowering. Apply according to the manufacturer's instructions for proper dosage.
Remove spent flowers to promote longer blooming. Use pruning shears to remove only damaged or dying branches in early spring before flowering, but leave all other branches intact. Removing old branches will reduce the number of flowers produced.