diff --git a/pandas/core/frame.py b/pandas/core/frame.py index 6158e19737185..d54a7318218b9 100644 --- a/pandas/core/frame.py +++ b/pandas/core/frame.py @@ -48,6 +48,7 @@ ) from pandas._libs.hashtable import duplicated from pandas._libs.lib import is_range_indexer +from pandas._libs.tslibs.timestamps import Timestamp from pandas.compat import PYPY from pandas.compat._constants import REF_COUNT from pandas.compat._optional import import_optional_dependency @@ -4180,6 +4181,14 @@ def __setitem__(self, key, value) -> None: ): # Column to set is duplicated self._setitem_array([key], value) + elif ( + # GH#61444 + isinstance(key, Hashable) + and key in self.columns + and is_scalar(value) + and isinstance(value, (Timestamp, np.datetime64)) + ): + self._set_item(key, [value] * len(self)) else: # set column self._set_item(key, value)