We have a caragana hedge that has not been trimmed for 4 years. The hedge in some places is 12 ft. tall with most of the folliage at the top of the plants. Previous trimming was at the 6 ft. level, so that is where most of the branching is on the stalks. I would like to shorten the hedge to a consistent 6 to 8 ft. and cause the plants to fill out. Is that possible and how do I do it?