Q.stimulating growth on side of hedge
I have an escallonia hedge about 6 feet high and over 2 feet thick. It is 16 year old. While the top grows vigorously the sides have become rather bare. Is there anything I can do about this?
The primary issue is most likely to be sunlight access, if the health tops is shading out the light to the sides.
Without a photo I can only guess based on experience, that pruning of the top will allow more sunlight to reach the lower portions on the sides. Thinning can help, if you or your gardener know how to get in there and open up the densely foliated top to allow some filtered light to penetrate. And/or height reduction pruning. Sometimes a radical reduction in spring is needed to stimulate new growth.
Another pruning technique is to shape the hedge with the lower portion wider and tapering in at the top. That way, even at high noon the sunlight can reach the lower portion of the hedge.
Good soil fertility and water management should also be considered.
https://www.gardeningknowhow.com/ornamental/shrubs/escallonia/growing-an-escallonia-hedge.htm