I recently moved into a new home with a nice yard. However, there are hedges in the backyard which have been trimmed into its current box-shape for many years without being pruned properly. Instead, it looks like they've been regularly shaved on the outside to maintain their shape. As a result, the hedges have a thin layer of green and flowering on the outside and top with thousands and thousands of dry twigs and branches on the inside. Below are photos of what I'm talking about. Any advice on how to clear these twigs and branches? I've tried cutting some of the branches and pulling them out, but I'm not sure how to deal with the thousands of dead twigs which i fear will take forever to clear. Any tips or suggestions would be highly appreciated. I'd like to maintain these shrubs going forward not in their current boxy shape, but more of a natural shape. I'd also like to reduce their size a bit so that I can prune them myself properly over time instead of having to pay my gardener extra to trim them.
One of the hedges consist of Bougainvilleas and I'm not sure of what the other one is. I live in the San Fernando valley in Southern California which is very warm. The Bougains on the inside seriously look like a series of birds nests because the thick, dense twigs are catching leaves.
Here is a photo of the Bougains from a distance:
Below are the close-ups of the twigs and branches:
Here is the other hedge. The boxy shape is less noticeable since I had instructed our gardener to stop trimming it.
And here is what the twigs look like: