Climbing hydrangea vines, Hydrangea anomala subspecies petiolaris, are a spectacular addition to the landscape, climbing to heights of 30 to 40 feet and producing masses of flowers. Vines propagated from softwood cuttings take three to five years to become established, but grow quickly once a good root system is in place. Take more cuttings than needed, and transplant the strongest plants.
Prepare a cup or tray of moist sand to receive the cutting. Pierce the bottom of the cup in three or four places to allow good drainage. Water the sand well, and allow the excess water to drain away.
Take a softwood cutting from a healthy climbing hydrangea vine in the early summer. Choose a section of new growth that is still flexible, but woody enough to break when bent back. Use a clean, sharp knife to make a straight cut. Avoid crushing or damaging the stem.Cut just below a leaf node, leaving a section of vine approximately four to six inches long.
Remove all flowers and the leaves from the lower half of the stem, leaving at least one set of leaves at the tip.
Dip the cutting in rooting hormone that has been prepared according to the package directions.
Punch a hole about two inches deep in the prepared sand with a pencil or twig. Insert the cutting into the hole, and press the sand in around the cutting to support it.
Keep the sand moist, and cover the cuttings with plastic to keep in the humidity. Use a few stakes to keep the plastic off the plants, and punch a few holes in the plastic to allow ventilation. Check the moisture in the sand daily, and add water as needed.
Place the covered plants in a bright, sunny window, but out of direct sunlight.
Check the cuttings after three to four weeks for root development. Gently remove the top layer of sand from one cutting to examine the roots. When the roots are well established, within four to eight weeks, remove the plastic and transplant the vines into a small container of potting mix.
Grow the rooted hydrangea vine in a sheltered location through the first winter, and transplant it in the landscape in the spring. Move the plants outside for a few hours daily, gradually increasing the time outdoors until the hydrangea vines are hardened off and ready to transplant to the landscape.