"When do roses die?"
Translation:Quand les roses meurent-elles ?
When used to ask a question, (quand) is always followed by an inversion. If the subject is a noun (here: les roses) then you will use complex inversion. That is, you invert the verb (here meurent) with a dummy pronoun (here "elles" because "les roses" is feminine plural )
Simple inversion: il meure --> quand meure-t-il?
Complex inversion: les roses meurent --> quand les roses meurent-elles?
If you want to do things simply you can always use est-ce que and not bother with the inversion: quand est-ce que les roses meurent?
I translated it with 'Des roses meurent quand?" - which was also accepted. But now I don't understand why both 'des' and 'les' seem ok. It's probably not related to the word order ('... meurent quand' versus 'quand meurent ..'), right? I recall similar confusion in the context of 'il aime le pain' for 'he loves bread' (because 'bread' without an article is usually translated 'du pain'). hmm, any suggestions?
Well I know that talking about roses in general needs "les" which is why it's the primary translation here... Whereas saying "des roses" means "some number of roses" since roses are countable, just like "du pain" means "some amount of bread" since bread is uncountable. That explains "il aime le pain" - he likes bread in general. Someone else can probably give you a better explanation for why "des roses" is also acceptable here though.