You don’t actually need to prune, but if you want a flush of more blooms and more flowering stems, you can do a bit of pruning the first few years. In the first year, prune about 6-12 inches to a node that has healthy buds. The location that you prune to will sprout two stems for later bloom in the year. Repeat this pruning every spring for three years, but prune a little higher the second and third year, so your plant will branch further up the vine. After the third year you will have a good base work of many stems. After that, only prune out dead or damaged canes.