diff --git a/plugins/calendar/calendar_ui.js b/plugins/calendar/calendar_ui.js
index 8add025b..27476418 100644
--- a/plugins/calendar/calendar_ui.js
+++ b/plugins/calendar/calendar_ui.js
@@ -1911,7 +1911,7 @@ function rcube_calendar_ui(settings)
 
     this.calendar_remove = function(calendar)
     {
-      if (confirm(rcmail.gettext('deletecalendarconfirm', 'calendar'))) {
+      if (confirm(rcmail.gettext(calendar.children ? 'deletecalendarconfirmrecursive' : 'deletecalendarconfirm', 'calendar'))) {
         rcmail.http_post('calendar', { action:'remove', c:{ id:calendar.id } });
         return true;
       }
@@ -1920,7 +1920,24 @@ function rcube_calendar_ui(settings)
 
     this.calendar_destroy_source = function(id)
     {
+      var delete_ids = [];
+
       if (this.calendars[id]) {
+        // find sub-calendars
+        if (this.calendars[id].children) {
+          for (var child_id in this.calendars) {
+            if (String(child_id).indexOf(id) == 0)
+              delete_ids.push(child_id);
+          }
+        }
+        else {
+          delete_ids.push(id);
+        }
+      }
+
+      // delete all calendars in the list
+      for (var i=0; i < delete_ids.length; i++) {
+        id = delete_ids[i];
         fc.fullCalendar('removeEventSource', this.calendars[id]);
         $(rcmail.get_folder_li(id, 'rcmlical')).remove();
         $('#edit-calendar option[value="'+id+'"]').remove();
diff --git a/plugins/calendar/drivers/kolab/kolab_driver.php b/plugins/calendar/drivers/kolab/kolab_driver.php
index 7ae80267..db0c5db4 100644
--- a/plugins/calendar/drivers/kolab/kolab_driver.php
+++ b/plugins/calendar/drivers/kolab/kolab_driver.php
@@ -122,6 +122,7 @@ class kolab_driver extends calendar_driver
         'default'  => $cal->storage->default,
         'active'   => $cal->storage->is_active(),
         'owner'    => $cal->get_owner(),
+        'children' => true,  // TODO: determine if that folder indeed has child folders
       );
     }
 
diff --git a/plugins/calendar/localization/de_CH.inc b/plugins/calendar/localization/de_CH.inc
index a418cb8e..cd3399fd 100644
--- a/plugins/calendar/localization/de_CH.inc
+++ b/plugins/calendar/localization/de_CH.inc
@@ -167,6 +167,7 @@ $labels['tabsharing'] = 'Freigabe';
 // messages
 $labels['deleteventconfirm'] = 'Möchten Sie diesen Termin wirklich löschen?';
 $labels['deletecalendarconfirm'] = 'Möchten Sie diesen Kalender mit allen Terminen wirklich löschen?';
+$labels['deletecalendarconfirmrecursive'] = 'Möchten Sie diesen Kalender mit allen Terminen und Unter-Kalendern wirklich löschen?';
 $labels['savingdata'] = 'Speichere Daten...';
 $labels['errorsaving'] = 'Fehler beim Speichern.';
 $labels['operationfailed'] = 'Die Aktion ist fehlgeschlagen.';
diff --git a/plugins/calendar/localization/de_DE.inc b/plugins/calendar/localization/de_DE.inc
index f5faa6fe..cb96b0d7 100644
--- a/plugins/calendar/localization/de_DE.inc
+++ b/plugins/calendar/localization/de_DE.inc
@@ -167,6 +167,7 @@ $labels['tabsharing'] = 'Freigabe';
 // messages
 $labels['deleteventconfirm'] = 'Möchten Sie diesen Termin wirklich löschen?';
 $labels['deletecalendarconfirm'] = 'Möchten Sie diesen Kalender mit allen Terminen wirklich löschen?';
+$labels['deletecalendarconfirmrecursive'] = 'Möchten Sie diesen Kalender mit allen Terminen und Unter-Kalendern wirklich löschen?';
 $labels['savingdata'] = 'Speichere Daten...';
 $labels['errorsaving'] = 'Fehler beim Speichern.';
 $labels['operationfailed'] = 'Die Aktion ist fehlgeschlagen.';
diff --git a/plugins/calendar/localization/en_US.inc b/plugins/calendar/localization/en_US.inc
index 7eb7063d..3bf52bae 100644
--- a/plugins/calendar/localization/en_US.inc
+++ b/plugins/calendar/localization/en_US.inc
@@ -172,6 +172,7 @@ $labels['tabsharing'] = 'Sharing';
 // messages
 $labels['deleteventconfirm'] = 'Do you really want to delete this event?';
 $labels['deletecalendarconfirm'] = 'Do you really want to delete this calendar with all its events?';
+$labels['deletecalendarconfirmrecursive'] = 'Do you really want to delete this calendar with all its events and sub-calendars?';
 $labels['savingdata'] = 'Saving data...';
 $labels['errorsaving'] = 'Failed to save changes.';
 $labels['operationfailed'] = 'The requested operation failed.';