diff --git a/wagtail/wagtailadmin/static/wagtailadmin/scss/layouts/page-editor.scss b/wagtail/wagtailadmin/static/wagtailadmin/scss/layouts/page-editor.scss
index 241932c84..1263cdb40 100644
--- a/wagtail/wagtailadmin/static/wagtailadmin/scss/layouts/page-editor.scss
+++ b/wagtail/wagtailadmin/static/wagtailadmin/scss/layouts/page-editor.scss
@@ -267,7 +267,8 @@
         }
 
         .struct-block .widget-text_input > label,
-        .struct-block .widget-textarea > label{
+        .struct-block .widget-textarea > label,
+        .struct-block .widget-admin_auto_height_text_input > label{
             display:none;
         }
 
diff --git a/wagtail/wagtailadmin/widgets.py b/wagtail/wagtailadmin/widgets.py
index 69282378d..6a2f146b4 100644
--- a/wagtail/wagtailadmin/widgets.py
+++ b/wagtail/wagtailadmin/widgets.py
@@ -17,14 +17,15 @@ from taggit.forms import TagWidget
 
 class AdminAutoHeightTextInput(WidgetWithScript, widgets.Textarea):
     def __init__(self, attrs=None):
-        # Use slightly better defaults than HTML's 20x2 box
+        # Use more appropriate rows default, given autoheight will alter this anyway
         default_attrs = {'rows': '1'}
         if attrs:
             default_attrs.update(attrs)
+
         super(AdminAutoHeightTextInput, self).__init__(default_attrs)
 
     def render_js_init(self, id_, name, value):
-        return '$("#{0}").autosize();'.format(json.dumps(id_))
+        return '$("#{0}").autosize();'.format(id_)
 
 class AdminDateInput(WidgetWithScript, widgets.DateInput):
     def render_js_init(self, id_, name, value):