poetry within text

When poetry comes after a paragraph of regular text and all poetry lines are indented the same is that considered "prose".

Here is the an example of what I mean:

(text)
and roses were listening to the voice, so quiet were they, for it was of them it sang.

In the starlight, in the starlight,
At the daylight's dewy close,
When the nightingale is singing
His last love song to the rose;

After doing some research on poetry I believe I understand that I should start at the left margin. Is this correct?

Thanks, Becky