Rooting Hydrangeas. Use sharp clippers to take cuttings about 6 inches down from the tip of the stem; then remove the lowest pair of leaves. Wet ends of cut stems, and dip into a rooting powder, such as Rootone, following the instructions on the label. Stick each cutting in moist potting soil, and place the pot in a shady location. Keep soil slightly moist. Cuttings root in 6-8 weeks.