The Endless Summer hydrangea is a unique hydrangea because it blooms on new wood, which means it will bloom several times during the growing season. This is important when trying to root a cutting from an Endless Summer hydrangea because you can take cuttings throughout the summer for propagation, although early summer is the best time. The new cutting, once rooted, will attempt to produce blooms fairly quickly even when the plant is small, but it is best to remove the flower bud at a leaf node. This will allow the plant to bush out and produce more leaves before using its energy to produce blooms.
Choose an early summer morning to take a cutting from the Endless Summer hydrangea when the plant is actively growing and most of the leaves are out for the season. Find a stem that is mostly green and growing and does not yet have a flower bud on the end.
Cut the stem just below the fourth leaf node or the area where the leaves come out of the stem counting down from the end of the stem. Do not damage the leaf node while cutting. Immediately immerse the cut end in a container of water.
Prepare the planting medium by mixing one-third perlite and two-thirds peat moss and putting mixture in a clean flower pot with a drainage hole in the bottom. Soak the planting medium with water until it is thoroughly wet. Let drain.
Remove the cutting from the container holding water and recut the hydrangea stem just under the next leaf node above the leaf node where it was originally cut. Remove the leaves from the leaf node above where you cut by pulling them down toward the cut end.
Dip the cut end of the hydrangea stem in the powdered rooting hormone covering the cut end as well as the node where the leaves were removed that is just above the cut end. Stick the end of the cutting into the planting medium. Be sure the end of the stem as well as the node covered with rooting hormone is covered with planting medium. Press the planting medium around the stem with your fingers so it will remain upright. Set in a warm area (70-85 degrees Fahrenheit) with bright light, but not direct sun, and mist daily to keep damp until cutting is actively growing, about six weeks.