Zero pad Drupal 7 Form API Date Control day and month HTML select element
I think you can use #date_format

  $format = 'm d Y';
  $form['date_from'] = array(
     '#type' =&gt; 'date',
     '#title' =&gt; t('select a date'),
     '#date_format' =&gt; $format,
   );


More values:
http://php.net/manual/en/function.date.php