def stringify_dates(dates):
    """
    Convert a datetime64 series to string in the form 'YYYY-M-D'.

    Parameters
    ----------
    dates : pandas.Series
        The numpy.datetime64 dates.

    Returns
    -------
    series : pandas.Series
        The string dates.
    """

    def stringify_date(date):

        try:
            date = ' '.join([
                '-'.join([
                    str(date.year),
                    str(date.month).zfill(2),
                    str(date.day).zfill(2)]),
                ':'.join([
                    str(date.hour).zfill(2),
                    str(date.minute).zfill(2),
                    str(date.second).zfill(2)])])
        except:
            pass

        return date

    series = dates.apply(stringify_date)
    series = series.astype('str')

    return series