For context, I have the following text speaking about the leaves of a maple tree.
I understand that the phrase in bold would be translated as something like "as for autumn, they are red" (and omit the leaves), but without context this phrase may not make sense.
If the subject was included, would the phrase look like "葉が秋は赤いです"?
Would it be correct and maintain the same meaning if に was used instead?
Would it be correct to use には instead too?
Edit: The phrases above are from the tadoku stories free books so I assume they are correct as is. I am just wondering whether I understood everything correctly.