I wanted to have portrait for page 1 and landscape for page 2. How could I achieve that in QGIS Print Composer?
You cannot mix portrait and landscape in the same print composer composition. You have to have two different print composers.
Did you consider to make use of atlas feature and then control page orientation by an attribute value of the atlas control featureclass?
Thank you for the above answer. It ended my search. So to have both layouts in the same document, what I did was, I rotated all items in the page that I wanted to be portrait using Item properties -> Rotation -> I rotated all to 270, then saved the file to PDF.