diff --git a/pandas/plotting/_matplotlib/converter.py b/pandas/plotting/_matplotlib/converter.py
index 8f2080658e63e..214a67690d695 100644
--- a/pandas/plotting/_matplotlib/converter.py
+++ b/pandas/plotting/_matplotlib/converter.py
@@ -1,7 +1,8 @@
 import contextlib
 import datetime as pydt
-from datetime import datetime, timedelta
+from datetime import datetime, timedelta, tzinfo
 import functools
+from typing import Optional, Tuple
 
 from dateutil.relativedelta import relativedelta
 import matplotlib.dates as dates
@@ -152,7 +153,7 @@ def axisinfo(unit, axis):
         return units.AxisInfo(majloc=majloc, majfmt=majfmt, label="time")
 
     @staticmethod
-    def default_units(x, axis):
+    def default_units(x, axis) -> str:
         return "time"
 
 
@@ -421,7 +422,7 @@ def autoscale(self):
         return self.nonsingular(vmin, vmax)
 
 
-def _from_ordinal(x, tz=None):
+def _from_ordinal(x, tz: Optional[tzinfo] = None) -> datetime:
     ix = int(x)
     dt = datetime.fromordinal(ix)
     remainder = float(x) - ix
@@ -450,7 +451,7 @@ def _from_ordinal(x, tz=None):
 # -------------------------------------------------------------------------
 
 
-def _get_default_annual_spacing(nyears):
+def _get_default_annual_spacing(nyears) -> Tuple[int, int]:
     """
     Returns a default spacing between consecutive ticks for annual data.
     """
diff --git a/pandas/plotting/_matplotlib/timeseries.py b/pandas/plotting/_matplotlib/timeseries.py
index eef4276f0ed09..193602e1baf4a 100644
--- a/pandas/plotting/_matplotlib/timeseries.py
+++ b/pandas/plotting/_matplotlib/timeseries.py
@@ -62,13 +62,13 @@ def _maybe_resample(series: "Series", ax, kwargs):
     return freq, series
 
 
-def _is_sub(f1, f2):
+def _is_sub(f1: str, f2: str) -> bool:
     return (f1.startswith("W") and is_subperiod("D", f2)) or (
         f2.startswith("W") and is_subperiod(f1, "D")
     )
 
 
-def _is_sup(f1, f2):
+def _is_sup(f1: str, f2: str) -> bool:
     return (f1.startswith("W") and is_superperiod("D", f2)) or (
         f2.startswith("W") and is_superperiod(f1, "D")
     )
diff --git a/pandas/plotting/_matplotlib/tools.py b/pandas/plotting/_matplotlib/tools.py
index caf2f27de9276..26b25597ce1a6 100644
--- a/pandas/plotting/_matplotlib/tools.py
+++ b/pandas/plotting/_matplotlib/tools.py
@@ -1,16 +1,22 @@
 # being a bit too dynamic
 from math import ceil
+from typing import TYPE_CHECKING, Tuple
 import warnings
 
 import matplotlib.table
 import matplotlib.ticker as ticker
 import numpy as np
 
+from pandas._typing import FrameOrSeries
+
 from pandas.core.dtypes.common import is_list_like
 from pandas.core.dtypes.generic import ABCDataFrame, ABCIndexClass, ABCSeries
 
 from pandas.plotting._matplotlib import compat
 
+if TYPE_CHECKING:
+    from matplotlib.table import Table
+
 
 def format_date_labels(ax, rot):
     # mini version of autofmt_xdate
@@ -21,7 +27,7 @@ def format_date_labels(ax, rot):
     fig.subplots_adjust(bottom=0.2)
 
 
-def table(ax, data, rowLabels=None, colLabels=None, **kwargs):
+def table(ax, data: FrameOrSeries, rowLabels=None, colLabels=None, **kwargs) -> "Table":
     if isinstance(data, ABCSeries):
         data = data.to_frame()
     elif isinstance(data, ABCDataFrame):
@@ -43,7 +49,7 @@ def table(ax, data, rowLabels=None, colLabels=None, **kwargs):
     return table
 
 
-def _get_layout(nplots, layout=None, layout_type="box"):
+def _get_layout(nplots: int, layout=None, layout_type: str = "box") -> Tuple[int, int]:
     if layout is not None:
         if not isinstance(layout, (tuple, list)) or len(layout) != 2:
             raise ValueError("Layout must be a tuple of (rows, columns)")
@@ -92,14 +98,14 @@ def _get_layout(nplots, layout=None, layout_type="box"):
 
 
 def _subplots(
-    naxes=None,
-    sharex=False,
-    sharey=False,
-    squeeze=True,
+    naxes: int,
+    sharex: bool = False,
+    sharey: bool = False,
+    squeeze: bool = True,
     subplot_kw=None,
     ax=None,
     layout=None,
-    layout_type="box",
+    layout_type: str = "box",
     **fig_kw,
 ):
     """
@@ -369,7 +375,7 @@ def _get_all_lines(ax):
     return lines
 
 
-def _get_xlim(lines):
+def _get_xlim(lines) -> Tuple[float, float]:
     left, right = np.inf, -np.inf
     for l in lines:
         x = l.get_xdata(orig=False)