The strategy I found useful was sticking to its behind.
Specifically the entire portion behind his front two legs. Once you are there he cant do much. All you gotta do after that is watch out for his AoE and movements that puit you in front .
Dodge the grab attack by leaving the target lock and just running in forward right or left direction.
I also used Raptor of the Mists to avoid his large slam attacks when he grows out his Hedges but can be dodged by rolling too. Just need good timing.
lastly dont get greedy as he punishes and punishes hard. So make sure dont punish him more than you need to.
good luck