Paniculata hydrangeas are beautiful plants with large blooms that can reach height of 25 feet and grow easily in a wide variety of soils. Propagating hydrangeas can be accomplished using different techniques. The most common and effective methods of propagating hydrangeas is by rooting cuttings from the plant or by using a ground layering method. Both take some patience but are rather simple.
Method 1: Rooting Cuttings
Take cuttings from a healthy paniculata hydrangea plant. Make cuttings that are 6 to 8 inches long, preferably from a branch that did not bloom. Remove the bottom leaves from the two leaf nodes at the bottom of the cutting. You may trim the larger leaves by cutting them in half.
Dip the severed end of the cutting in rooting hormone and insert it in a cup filled with moist vermiculite. You should perforate the bottom of the cup to ensure proper drainage. Firm the soil lightly around the cutting. The base two leaf nodes should be in the soil. Water until it drains out the bottom.
Cut the top of the 2-liter soda bottle below the spout, at the wide part of the bottle. Turn the bottle upside down and place it over the cutting and the cup. You now have a miniature green house.
Place the cutting in bright but indirect sunlight. Keep the soil moist by watering every three days or whenever needed. Keep the cutting in the same cup until it grows big enough to be transplanted in a larger container or in your garden.
Method 2: Ground Layering
Choose an outside branch of the live paniculata hydrangea. Do not cut the branch. Pick off the leaves 10 inches from the base the branch. Scraping a little bark on the branch will also help, but leave the leaf nodes intact. Sprinkle the branch with rooting hormone.
Dig a 3-inch deep ditch long enough to accommodate the 10-inch section of the branch with the leaves removed from the leaf nodes and the area where the bark was scraped. Place the branch into the ditch, cover with soil and firm the soil.
Place a flat rock or cinder block on top of the surface of the soil where the branch is buried. Do not disturb the branch for two to three months.
Cut the branch from the donor plant when the new roots are well established. Do not remove the branch yet, but instead let it sit in place for about three more weeks to build strength. Then, you may carefully dig up the new plant and replant it in a large pot or somewhere else in your garden.