At its best:
Jun, Jul, Aug
From the stems you have removed from the bush, cut a section 20-25cm long and as thick as a pencil. Ensure there is a bud at both the top and bottom of the cutting, and remember which end is the top. Aim to have five or six buds per cutting.
In your cuttings bed, make a narrow, 10-cm-deep, v-shaped trench by pressing the soil back with a spade. Then simply insert your cuttings (the right way up), spacing them at least 10cm apart.
Firm the cuttings gently by hand. The surface level will drop, but make sure that half of the cutting or at least two buds are under the soil surface. The buds above the surface will break leaf in spring.
Use your feet to firm the cuttings into the row. This will stop them lifting up when the ground is frozen, and will also reduce any movement, improving rooting. The cuttings will have grown roots by next summer, but leave them in place until September, when you can transplant them to their final growing positions.