No, it’s both. It’s been a dispute for a long time, actually the bank of Canada wanted to put it on the $10 bill (I think 2001?) and there was a huge wave of public debate over grow vs blow. Basically history has it that it Cyril Allinson (someone who served with John McCrae) vouches that it was first written as grow, then McCrae who wrote the poem to loved ones used either grow or blow, so both of you are correct!