Index: src/wp-includes/ms-functions.php
===================================================================
--- src/wp-includes/ms-functions.php	(revision 34912)
+++ src/wp-includes/ms-functions.php	(working copy)
@@ -1317,7 +1317,7 @@
  * @param string $blog_title The title of the new site.
  */
 function install_blog( $blog_id, $blog_title = '' ) {
-	global $wpdb, $wp_roles;
+	global $wpdb, $wp_roles, $current_site;
 
 	// Cast for security
 	$blog_id = (int) $blog_id;
@@ -1339,10 +1339,21 @@
 	// populate_roles() clears previous role definitions so we start over.
 	$wp_roles = new WP_Roles();
 
-	$url = untrailingslashit( $url );
+	$siteurl = $home = untrailingslashit( $url );
 
-	update_option( 'siteurl', $url );
-	update_option( 'home', $url );
+	if ( ! is_subdomain_install() ) {
+
+ 		if ( 'https' === parse_url( get_network_option( 'siteurl' ), PHP_URL_SCHEME ) ) {
+ 			$siteurl = set_url_scheme( $siteurl, 'https' );
+ 		}
+ 		if ( 'https' === parse_url( get_home_url( $current_site->blog_id ), PHP_URL_SCHEME ) ) {
+ 			$home = set_url_scheme( $home, 'https' );
+ 		}
+
+	}
+
+	update_option( 'siteurl', $siteurl );
+	update_option( 'home', $home );
 
 	if ( get_site_option( 'ms_files_rewriting' ) )
 		update_option( 'upload_path', UPLOADBLOGSDIR . "/$blog_id/files" );
Index: tests/phpunit/tests/multisite/site.php
===================================================================
--- tests/phpunit/tests/multisite/site.php	(revision 34912)
+++ tests/phpunit/tests/multisite/site.php	(working copy)
@@ -1000,6 +1000,67 @@
 		$blogaddress = get_blogaddress_by_id( 42 );
 		$this->assertEquals( '', $blogaddress );
 	}
+
+	/**
+	 * @ticket 33620
+	 * @dataProvider data_new_blog_url_schemes
+	 */
+	function test_new_blog_url_schemes( $home_scheme, $siteurl_scheme, $force_ssl_admin ) {
+		$current_site = get_current_site();
+
+		$home    = get_option( 'home' );
+		$siteurl = get_site_option( 'siteurl' );
+		$admin   = force_ssl_admin();
+
+		// Setup:
+		update_option( 'home', set_url_scheme( $home, $home_scheme ) );
+		update_site_option( 'siteurl', set_url_scheme( $siteurl, $siteurl_scheme ) );
+		force_ssl_admin( $force_ssl_admin );
+
+		// Install:
+		$new = wpmu_create_blog( $current_site->domain, '/new-blog/', 'New Blog', get_current_user_id() );
+
+		// Reset:
+		update_option( 'home', $home );
+		update_site_option( 'siteurl', $siteurl );
+		force_ssl_admin( $admin );
+
+		// Assert:
+		$this->assertNotWPError( $new );
+		$this->assertSame( $home_scheme, parse_url( get_blog_option( $new, 'home' ), PHP_URL_SCHEME ) );
+		$this->assertSame( $siteurl_scheme, parse_url( get_blog_option( $new, 'siteurl' ), PHP_URL_SCHEME ) );
+	}
+
+	function data_new_blog_url_schemes() {
+		return array(
+			array(
+				'https',
+				'https',
+				false,
+			),
+			array(
+				'http',
+				'https',
+				false,
+			),
+			array(
+				'https',
+				'http',
+				false,
+			),
+			array(
+				'http',
+				'http',
+				false,
+			),
+			array(
+				'http',
+				'http',
+				true,
+			),
+		);
+	}
+
 }
 
 endif;