Feeding established privet

Hi all I have never had to feed or water my privet hedge but as it is now dying in places I was going to try fish blood and bone, fresh compost and plenty of watering. Is there anything else I should be doing? 

Also I have seen a hedgehog recently in the area of hedge that I will be trying to revive so I also want to check if anyone would know if the fish blood and bond could be harmful at all? 

Thank you