I play as melee character and I am stuck at stage 7 with boss fight. Tried few hundred times and can't pass him

So need an advice from melee player who had beaten it. I most of the time die from poison dots that exploding plants give me. It hits for 5.3k initially and another 5.3k after 1 sec, close to 11k in 1st sec and I die 90% time before I can remove it.
Is there a way to tell which plant will explode, sometimes they do nothing when u come close. It seems pretty random but I never managed to avoid it?
I have 20.5k hp, vigor etc. Stam nb 501 CP
Thanx in advance