diff -u b/core/modules/text/src/Plugin/Field/FieldWidget/TextareaWidget.php b/core/modules/text/src/Plugin/Field/FieldWidget/TextareaWidget.php
--- b/core/modules/text/src/Plugin/Field/FieldWidget/TextareaWidget.php
+++ b/core/modules/text/src/Plugin/Field/FieldWidget/TextareaWidget.php
@@ -26,7 +26,21 @@
    */
   public function settingsForm(array $form, FormStateInterface $form_state) {
     $element = parent::settingsForm($form, $form_state);
-    $element['rows']['#description'] = $this->t('<a href=":url">Text editors</a> might display a different number of rows.', [':url' => Url::fromRoute('help.page', ['name' => 'editor'])->toString()]);
+
+    // Add description text informing site builders that the "Rows" setting
+    // isn't always respected by text editors.
+    $description = '';
+    $module_handler = \Drupal::moduleHandler();
+    if ($module_handler->moduleExists('editor')) {
+      if ($module_handler->moduleExists('help')) {
+        $description = $this->t('<a href=":editor_help">Text editors</a> might display a different number of rows.', [':url' => Url::fromRoute('help.page', ['name' => 'editor'])->toString()]);
+      }
+      else {
+        $description = $this->t('Text editors might display a different number of rows. Enable the Help module to learn more about text editors.');
+      }
+    }
+    $element['rows']['#description'] = $description;
+
     return $element;
   }