Disable past dates in date_combo
Use hook_date_combo_process_alter(&amp;$element, &amp;$form_state, $context).

I have used it in commerce discount module: while adding discount.

Example :

  $current_path = current_path();
  if ($current_path == "admin/commerce/store/discounts/add") {
   $element["value"]['#datepicker_options'] = array(
     'minDate' =&gt; 0,
   );
   $element["value2"]['#datepicker_options'] = array(
    'minDate' =&gt; 0,
   );    
  }