You look funny by frustrating over such simple issue because by the tone of your topic it seems you haven't even considered to analyse what's going on.
Here's some tips, don't let her use her white: use Spirit Wolf. Or Medusa. Or Comic Elf. Or Bone (with legendary).
So many options to counter.
And stop playing on auto or spamming your whites which causes enemy plant soul unable to exit from her white also.
As a fair note Plant Soul sometimes bugs out during her white, try not to use anything while she won't end exit animation.