<input type="text" class="form-control" name="wfitem_<?=$item->name?>" id="wfitem_<?=$item->name?>_<?=$$wftype->id?>" value="<?=$item->value->value_string?>" placeholder="<?=$item->placeholder?>" />

<script type="text/javascript">
  $('#wfitem_<?=$item->name?>_<?=$$wftype->id?>').datepicker({
      language: 'de',
      format: "dd.mm.yyyy",
      showWeekDays: true,
      todayBtn: 'linked',
      autoclose: true
  });
</script>