diff --git a/wagtail/wagtailadmin/blocks.py b/wagtail/wagtailadmin/blocks.py
index 4617f701b..feb8946fd 100644
--- a/wagtail/wagtailadmin/blocks.py
+++ b/wagtail/wagtailadmin/blocks.py
@@ -541,7 +541,8 @@ class StructBlock(six.with_metaclass(DeclarativeSubBlocksMetaclass, BaseStructBl
 
 class ListBlock(Block):
     class Meta:
-        default = []
+        # Default to a list consisting of one empty child item (using None to trigger the child's empty / default rendering)
+        default = [None]
 
     def __init__(self, child_block, **kwargs):
         super(ListBlock, self).__init__(**kwargs)
diff --git a/wagtail/wagtailcore/fields.py b/wagtail/wagtailcore/fields.py
index 6b1a3316a..aaba01317 100644
--- a/wagtail/wagtailcore/fields.py
+++ b/wagtail/wagtailcore/fields.py
@@ -55,7 +55,7 @@ class StreamField(with_metaclass(models.SubfieldBase, models.Field)):
         return name, path, args, kwargs
 
     def to_python(self, value):
-        if value is None:
+        if value is None or value == '':
             return StreamValue(self.stream_block, [])
         elif isinstance(value, StreamValue):
             return value