Modify Date Format to German

WordPress has a special function for translating dates, called date_i18n. General usage:

echo date_i18n( $dateformatstring, $unixtimestamp, $gmt);

Supposing you have German as your site’s language this would be:

echo date_i18n( 'j. F Y', false, false);

You can also import the time format from the admin settings, like this:

echo date_i18n(get_option('date_format'), false, false);