Shortcode won't work in filter

I'm using a well known filter function to automatically add text in new posts. Works like a charm But if I try to add a Gravity form shortcode in there it fails. Why? Is there any way to get the shortcode to work?

<?php
add_filter( 'default_content', 'my_editor_content' );

function my_editor_content( $content ) {
	$content = "[gravityform id="1" name="testform" description="false"]";
	return $content;
}
?>

Brilliant! Thanks so much :-)