$date_array = array();
if( !empty($row_edit) ){
    $stageDates = explode(', ',$row_edit['placement_stage_date']);
    foreach( $stageDates as $stageDate ){
        //echo $stageDate.'
';
        $date_array[] = $stageDate;
    }
}
// print $stageDate value outside of loop, something like this