I don’t really find it grammatically very wrong, it’s just missing a question mark. And it’s wrong to dismiss sentences for being slightly wrong on a language website.
What woke up the little plant?
Who woke up the little plant?
Note that in this context, hindi does not differentiate between what and who. I.e. the translation for the both the above phrases is the same, as below:
Nanhe paudhe ko kisne jagaya?
नन्हे पौधे को किसने जगाय?