diff --git a/scanpy/plotting/_anndata.py b/scanpy/plotting/_anndata.py
index ef6ae9119b..f77c46ed94 100755
--- a/scanpy/plotting/_anndata.py
+++ b/scanpy/plotting/_anndata.py
@@ -878,7 +878,7 @@ def rename_cols_to_int(value):
         else:
             width, height = figsize
 
-        num_rows = len(categories)
+        num_rows = len(var_names)
         height_ratios = None
         if has_var_groups:
             # add some space in case 'brackets' want to be plotted on top of the image