Hydrangea cuttings grow and benefit from prompt placement in the rooting material, treatment with root-promoting compounds and the use of a lightweight soil that provides sufficient aeration. A mixture of perlite with an equal part of peat moss makes an ideal rooting material for hydrangea cuttings.
Cuttings that tend to rot before taking root are receiving too much moisture, and need a drier potting mixture with perlite or vermiculite to increase the air in the container. Auxin is a natural plant hormone that stimulates root growth when applied to the base of the cut. Synthetic hormone options are available, and come in powder and liquid forms. Hydrangea cuttings are quicker to root in a potting mixture with a temperature from 65 to 75 degrees Fahrenheit, and should be kept away from excessive heat or cold.
Hydrangea propagation can be performed with softwood or hardwood cuttings. During the rooting period, cuttings need to be exposed to light, but not placed in direct sunlight, as hardwood cuttings have energy reserves stored in their woody stems. The initial cutting needs to come from a healthy plant, ideally after watering the hydrangea on the day prior to cutting. Flowers or buds on the cutting must be removed to ensure all the energy goes into forming new roots.