diff --git a/doc/source/whatsnew/v3.0.0.rst b/doc/source/whatsnew/v3.0.0.rst
index 6121f2097a2f1..bb74a68ca9445 100644
--- a/doc/source/whatsnew/v3.0.0.rst
+++ b/doc/source/whatsnew/v3.0.0.rst
@@ -1249,6 +1249,7 @@ Plotting
 - Bug in :meth:`Series.plot` preventing a line and bar from being aligned on the same plot (:issue:`61161`)
 - Bug in :meth:`Series.plot` preventing a line and scatter plot from being aligned (:issue:`61005`)
 - Bug in :meth:`Series.plot` with ``kind="pie"`` with :class:`ArrowDtype` (:issue:`59192`)
+- Bug in plotting with a :class:`TimedeltaIndex` with non-nanosecond resolution displaying incorrect labels (:issue:`63237`)
 
 Groupby/resample/rolling
 ^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/pandas/plotting/_matplotlib/converter.py b/pandas/plotting/_matplotlib/converter.py
index 5d06cbb8e8d2e..813bd984cf297 100644
--- a/pandas/plotting/_matplotlib/converter.py
+++ b/pandas/plotting/_matplotlib/converter.py
@@ -1107,7 +1107,7 @@ def __init__(self, unit: TimeUnit = "ns"):
     axis: Axis
 
     @staticmethod
-    def format_timedelta_ticks(x, pos, n_decimals: int, exp: int) -> str:
+    def format_timedelta_ticks(x, pos, n_decimals: int, exp: int = 9) -> str:
         """
         Convert seconds to 'D days HH:MM:SS.F'
         """