You mean 핍니까?
"벚꽃은" 왜 틀립니까?
Why not: 벚꽃은 언제 펴요?
This is my question. It seems like itʼs a question about cherry blossoms in general.
EDIT: Three months later (April 2021), I tried 벚꽃은 언제 핍니까? and it was accepted.
Shouldn't 언제 be at the beginning of the sentence?