Many plants including a wide range of deciduous shrubs such as philadelphus, hydrangea, deutzia, weigela and buddleja can be propagated by softwood cuttings in early summer. Softwood cuttings are taken from new shoots that are still young and have not yet started to firm up and turn woody.
They should root in three to four weeks as long as you are able to provide the correct conditions, which are a cool moist, environment around the tops of the cuttings and shade from the sun. An enclosed propagator on a north-facing windowsill or shaded greenhouse is ideal and will provide the humidity needed to prevent the soft cuttings from wilting until roots develop. Most softwood cuttings will root without additional heat in the summer, although a little gentle base heat can help roots to develop as long as you can keep the tops of the cuttings cool and hydrated by regular misting with water.
When trimmed and prepared, the base of the cuttings can be treated with a rooting compound to encourage roots, although many shrubs will root without it. As for compost you need a mix that retains moisture and also has good air porosity to help root development. You can easily create this by mixing together three parts multipurpose compost with two parts perlite or vermiculite.
Step by step
Collect the cuttings in early morning when it's cool and pop them into a damp polythene bag to prevent wilting
Trim the cuttings to legnth (approx 7.5cm) just below a leaf joint and remove the lower leaves to create a clear stem
If you use a rooting hormone, treat the base of the cutting and insert into trays of cutting compost
Place the cuttings into the propagator and water. Mist regularly or cover with thin polythene to create humid conditions