Do you need to use đóa when talking about specific flowers? Ví dụ, đóa hoa hồng này
it's a classifier for flowers, synonymous with bông. you sure can use it with specific flowers. you can say "đoá hoa hồng" or just "đoá hồng".
Doa hoa was flower petals? I first heard it in the song TINH YEU TUYET VOI...from the great SAIGON ROCKS album.