diff --git a/src/calibre/db/backend.py b/src/calibre/db/backend.py
index 38e61ab47e..05d30ca5fc 100644
--- a/src/calibre/db/backend.py
+++ b/src/calibre/db/backend.py
@@ -1261,6 +1261,8 @@ class DB:
 
     def close(self, force=False, unload_formatter_functions=True):
         if getattr(self, '_conn', None) is not None:
+            if self.prefs['expire_old_trash_after'] == 0:
+                self.expire_old_trash(0)
             if unload_formatter_functions:
                 try:
                     unload_user_template_functions(self.library_id)
@@ -2021,7 +2023,7 @@ class DB:
                     mtime = st.st_mtime
                 except OSError:
                     mtime = 0
-                if mtime + expire_age_in_seconds <= now:
+                if mtime + expire_age_in_seconds <= now or expire_age_in_seconds <= 0:
                     removals.append(x.path)
         for x in removals:
             rmtree_with_retry(x)
diff --git a/src/calibre/gui2/trash.py b/src/calibre/gui2/trash.py
index aa210d3b6b..a6f0c91645 100644
--- a/src/calibre/gui2/trash.py
+++ b/src/calibre/gui2/trash.py
@@ -134,11 +134,15 @@ class TrashView(Dialog):
 
         la = QLabel(_('&Permanently delete after:'))
         self.auto_delete = ad = QSpinBox(self)
-        ad.setMinimum(1)
+        ad.setMinimum(0)
         ad.setMaximum(365)
+        ad.setSpecialValueText(_('on close'))
         ad.setValue(int(self.db.pref('expire_old_trash_after', DEFAULT_TRASH_EXPIRY_TIME_SECONDS) / 86400))
         ad.setSuffix(_(' days'))
-        ad.setToolTip(_('Deleted items are permanently deleted automatically after the specified number of days'))
+        ad.setToolTip(_(
+            'Deleted items are permanently deleted automatically after the specified number of days. If set to "on close" they are'
+            ' deleted whenever the library is closed, that is when switching to another library or exiting calibre.'
+        ))
         ad.valueChanged.connect(self.trash_expiry_time_changed)
         h = QHBoxLayout()
         h.addWidget(la), h.addWidget(ad), h.addStretch(10)