The climbing hydrangea, or Hydrangea petiolaris, is a dazzling perennial vine that produces large clusters of white blossoms. Slow-growing and shade-loving, the climbing hydrangea can climb to 16 metres, growing aerial roots that attach to walls, fences and even trees. Climbing hydrangeas are one of the easiest plants to propagate from stem cuttings. Take your cuttings in late summer, and by spring you'll have a whole new crop of climbing hydrangeas to plant in your garden.
Take a climbing hydrangea cutting that has at least two or three leaf joints. Remove the lower leaves from the cutting, and cut the largest leaves in half.
Remove any flower heads from the cutting. This will help direct energy toward growing new roots instead of toward flowering.
Fill a 10 cm planter pot with a mixture of equal parts coarse sand and peat moss.
Dip the severed end of the cutting in rooting hormone. Insert the cutting into the potting mixture, just deep enough so the cutting can stand erect on its own. Limit the number of cuttings to three per planter pot.
Water the newly planted cuttings well, soaking the potting medium and ensuring that the water drains freely through the holes in the bottom of the pot. Don't water again until the top layer of the potting medium feels slightly dry.
Place the pot in a greenhouse or on a windowsill that receives bright, indirect sunlight. Cover the pot with plastic, inserting stakes in the potting soil to tent the plastic and keep it from touching the cuttings.
Maintain a constant temperature, between 21C and 27C, day and night.
Transfer the cuttings to individual pots after they have rooted, usually after about 10 to 20 days. Pinch off the top of the plant to encourage it to grow side shoots.
Plant the rooted cuttings outdoors in the spring.
If you're not sure whether your climbing hydrangea cutting has developed adequate roots, tug gently on the cutting. If the cutting resists your slight tug, it has started to root.
Getting your climbing hydrangea cuttings to survive through the winter indoors can be difficult. If your cuttings are not doing well, try sinking the planter pot with the cutting into the ground and cover around the cutting with sawdust mulch.