diff --git a/django/contrib/admin/options.py b/django/contrib/admin/options.py
index 946e074624..524ecf4938 100644
--- a/django/contrib/admin/options.py
+++ b/django/contrib/admin/options.py
@@ -212,7 +212,8 @@ class ModelAdmin(object):
         # For DateTimeFields, use a special field and widget.
         if isinstance(db_field, models.DateTimeField):
             return forms.SplitDateTimeField(required=not db_field.blank,
-                widget=widgets.AdminSplitDateTime(), label=capfirst(db_field.verbose_name), **kwargs)
+                widget=widgets.AdminSplitDateTime(), label=capfirst(db_field.verbose_name),
+                help_text=db_field.help_text, **kwargs)
 
         # For DateFields, add a custom CSS class.
         if isinstance(db_field, models.DateField):
diff --git a/django/contrib/admin/templates/admin/change_form.html b/django/contrib/admin/templates/admin/change_form.html
index 7485f2fbf7..4889557abb 100644
--- a/django/contrib/admin/templates/admin/change_form.html
+++ b/django/contrib/admin/templates/admin/change_form.html
@@ -54,7 +54,7 @@
             {% else %}
                 {{ field.label_tag }}{{ field.field }}
             {% endif %}
-            {% if field.help_text %}<p class="help">{{ field.help_text }}</p>{% endif %}
+            {% if field.field.field.help_text %}<p class="help">{{ field.field.field.help_text }}</p>{% endif %}
         {% endfor %}
         </div>
     {% endfor %}
diff --git a/django/db/models/fields/__init__.py b/django/db/models/fields/__init__.py
index 8fe0c20102..157eede01a 100644
--- a/django/db/models/fields/__init__.py
+++ b/django/db/models/fields/__init__.py
@@ -736,7 +736,7 @@ class NullBooleanField(Field):
         return [oldforms.NullBooleanField]
 
     def formfield(self, **kwargs):
-        defaults = {'required': not self.blank, 'label': capfirst(self.verbose_name)}
+        defaults = {'required': not self.blank, 'label': capfirst(self.verbose_name), 'help_text': self.help_text}
         defaults.update(kwargs)
         return forms.NullBooleanField(**defaults)