Hydrangeas are old-fashioned shrubs that provide a stunning display of blooms year after year, beautiful on the bush or in cut flower bouquets. Hydrangeas are sturdy plants with simple needs that can thrive as long as they have enough water and sunlight. Even novice gardeners will find it easy to start a new hydrangea from an existing bush. Take a cutting from a healthy hydrangea in late spring or early summer.
Remove a 5- to 6-inch section of stem from an existing hydrangea bush. Trim off the bloom, and pinch off the leaves on the lower half of the stem. Leave an upper set of leaves intact, but cut them down by half with a pair of clean scissors.
Fill a small planting container with a mixture of half potting soil and half perlite. Moisten the soil with a spray bottle. Dip the cut end of the hydrangea stem in rooting hormone and plant it in the soil.
Put a plastic bag over the hydrangea stem and put some stakes in the soil to keep the stem from touching the plastic. Put the planting container where it will get sunlight, but keep it out of direct sunlight, which will be too hot.
Check the soil occasionally. The plastic should keep the soil damp, but if it appears to be drying out, remove the plastic and mist the soil lightly.
Leave the hydrangea stem under plastic until it takes root, which will take about two to three weeks. Tug on the hydrangea stem gently, and if you feel slight resistance, the stem has taken root. You may also be able to see the tiny white roots through the hole in the bottom of the planting container.
Plant the hydrangea outside if you live in a warm climate. If temperatures in your area drop below freezing in the winter, keep the hydrangea indoors until spring. Move it into bright sunlight and keep the soil just slightly damp--too much moisture can cause the stem to rot.