They are easy to root , "semi hardwood cuttings" this years growth about July would be the ideal time.

Select 75-150mm (3”-6”) long non-flowering side shoots and cut them off the main stems, make the cut just below a node. (just under where the leaves come from)

Take the cuttings in the morning and give the plant a good water the night before. (Place in a plastic bag straight away to keep them fresh)

Remove the soft tip, strip the leaves from the lower half of the stem and dip the base in a hormone rooting powder.

Use Multi purpose and add some extra grit or horticultural sand to the mix , and using a pencil or your finger make a hole around the edge of the pot and put the cuttings in so the leaf is just above the compost.

Once completed give it a water let it drain for 30 mins and then place a clear plastic bag over the pot and put some where shady.

They should root in 3 to 4 weeks , you can keep in the pot but it will need protection over the winter so a greenhouse or cloche would be ideal.
In the spring about late March early April I would separate each plant and put in its own pot and grow on and plant out when looking big enough to cope with the big out doors, and when frost is over with.

Other's on here may have other ways of doing it but I find this the easiest method for me and works 90% of the time.

Gg