diff --git a/holidays/countries/thailand.py b/holidays/countries/thailand.py
index 6d04bc338..73e5d1ce8 100644
--- a/holidays/countries/thailand.py
+++ b/holidays/countries/thailand.py
@@ -90,7 +90,10 @@ class Thailand(ObservedHolidayBase, InternationalHolidays, StaticHolidays, ThaiC
         - [Royal Ploughing Ceremony]
             https://en.wikipedia.org/wiki/Royal_Ploughing_Ceremony
             https://www.lib.ru.ac.th/journal/may/may_phauchmongkol.html
-            `<https://www.myhora.com/ปฏิทิน/ปฏิทิน-พ.ศ.2540.aspx>`_
+            https://dl.parliament.go.th/handle/20.500.13072/103428
+            https://dl.parliament.go.th/handle/20.500.13072/92816
+            https://e-manage.mju.ac.th/timeline_detail.aspx?key=MTk4
+            https://resolution.soc.go.th/PDF_UPLOAD/2510/932141.pdf
         - [Royal Thai Armed Forces Day]
             `<https://th.wikipedia.org/wiki/วันกองทัพไทย>`_
         - [Teacher's Day]
@@ -522,18 +525,59 @@ def _populate_government_holidays(self):
         # No Future Fixed Date Holidays
 
         # วันพืชมงคล
-        # Restarts in 1957 (B.E. 2500).
+        # Restarts in 1947 (B.E. 2490), wouldn't become an holiday again until 1960 (B.E. 2503).
+        # Removed as an holiday in 1999 due to financial crisis, reinstated in 2000.
+        # No event was held in 2021 due to local Covid-19 situation, though it stays a day off.
         # Is dated on an annual basis by the Royal Palace, always on weekdays.
+        # For historic research, วันเกษตรแห่งชาติ (National Agricultural Day) also concides with
+        #   this from 1966 onwards. For earlier records the date was refered as วันแรกนาขวัญ.
         # This isn't even fixed even by the Thai Lunar Calendar, but instead
-        #   by Court Astrologers; All chosen dates are all around May, so we
-        #   can technically assign it to 13 May for years prior with no data.
+        #   by Court Astrologers; All chosen dates are all in the first three weeks of May.
         # *** NOTE: only observed by government sectors.
         # TODO: Update this annually around Dec of each year.
 
+        # Got only 1 source for 1992 and 1993, might need some recheck later.
         raeknakhwan_dates = {
-            1997: (MAY, 13),
-            1998: (MAY, 13),
-            # Not held in 1999 date.
+            1960: (MAY, 2),
+            1961: (MAY, 11),
+            1962: (MAY, 7),
+            1963: (MAY, 10),
+            1964: (MAY, 8),
+            1965: (MAY, 13),
+            1966: (MAY, 13),
+            1967: (MAY, 11),
+            1968: (MAY, 10),
+            1969: (MAY, 9),
+            1970: (MAY, 8),
+            1971: (MAY, 7),
+            1972: (MAY, 8),
+            1973: (MAY, 7),
+            1974: (MAY, 8),
+            1975: (MAY, 7),
+            1976: (MAY, 10),
+            1977: (MAY, 12),
+            1978: (MAY, 11),
+            1979: (MAY, 7),
+            1980: (MAY, 14),
+            1981: (MAY, 7),
+            1982: (MAY, 19),
+            1983: (MAY, 11),
+            1984: (MAY, 10),
+            1985: (MAY, 9),
+            1986: (MAY, 9),
+            1987: (MAY, 8),
+            1988: (MAY, 11),
+            1989: (MAY, 11),
+            1990: (MAY, 11),
+            1991: (MAY, 10),
+            1992: (MAY, 14),
+            1993: (MAY, 17),
+            1994: (MAY, 11),
+            1995: (MAY, 10),
+            1996: (MAY, 16),
+            1997: (MAY, 9),
+            1998: (MAY, 8),
+            # Not a holiday in 1999 date, was held on MAY, 14.
             2000: (MAY, 15),
             2001: (MAY, 16),
             2002: (MAY, 9),
@@ -544,7 +588,7 @@ def _populate_government_holidays(self):
             2007: (MAY, 10),
             2008: (MAY, 9),
             2009: (MAY, 11),
-            2010: (MAY, 10),
+            2010: (MAY, 13),
             2011: (MAY, 13),
             2012: (MAY, 9),
             2013: (MAY, 13),
@@ -555,11 +599,12 @@ def _populate_government_holidays(self):
             2018: (MAY, 14),
             2019: (MAY, 9),
             2020: (MAY, 11),
-            2021: (MAY, 13),
-            2022: (MAY, 17),
-            2023: (MAY, 11),
+            2021: (MAY, 10),
+            2022: (MAY, 13),
+            2023: (MAY, 17),
+            2024: (MAY, 10),
         }
-        if 1957 <= self._year <= 2023 and self._year != 1999:
+        if 1960 <= self._year <= 2024 and self._year != 1999:
             self._add_observed(
                 # Royal Ploughing Ceremony.
                 self._add_holiday(tr("วันพืชมงคล"), raeknakhwan_dates.get(self._year, (MAY, 13)))
@@ -795,7 +840,9 @@ class ThailandStaticHolidays:
             (JUL, 31, thai_bridge_public_holiday),
             (DEC, 29, thai_bridge_public_holiday),
         ),
+        2024: (DEC, 30, thai_bridge_public_holiday),
     }
+    special_workday_holidays = {1999: (MAY, 14, tr("วันพืชมงคล"))}
 
     special_public_holidays_observed = {
         2007: (DEC, 24, thai_election),
diff --git a/snapshots/countries/TH_COMMON.json b/snapshots/countries/TH_COMMON.json
index 1c14fabac..f3afbccf4 100644
--- a/snapshots/countries/TH_COMMON.json
+++ b/snapshots/countries/TH_COMMON.json
@@ -122,7 +122,7 @@
     "1957-04-06": "Chakri Memorial Day",
     "1957-04-13": "Songkran Festival",
     "1957-04-15": "National Mother's Day",
-    "1957-05-13": "Royal Ploughing Ceremony; Visakha Bucha",
+    "1957-05-13": "Visakha Bucha",
     "1957-06-24": "National Day",
     "1957-07-01": "Mid-Year Closing Day",
     "1957-07-12": "Asarnha Bucha",
@@ -140,7 +140,6 @@
     "1958-04-06": "Chakri Memorial Day",
     "1958-04-13": "Songkran Festival",
     "1958-05-05": "Coronation Day",
-    "1958-05-13": "Royal Ploughing Ceremony",
     "1958-06-02": "Visakha Bucha",
     "1958-06-24": "National Day",
     "1958-07-01": "Mid-Year Closing Day",
@@ -160,7 +159,6 @@
     "1959-04-08": "Royal Thai Armed Forces Day",
     "1959-04-13": "Songkran Festival",
     "1959-05-05": "Coronation Day",
-    "1959-05-13": "Royal Ploughing Ceremony",
     "1959-05-22": "Visakha Bucha",
     "1959-06-24": "National Day",
     "1959-07-01": "Mid-Year Closing Day",
@@ -179,9 +177,9 @@
     "1960-04-06": "Chakri Memorial Day",
     "1960-04-08": "Royal Thai Armed Forces Day",
     "1960-04-13": "Songkran Festival",
+    "1960-05-02": "Royal Ploughing Ceremony",
     "1960-05-05": "Coronation Day",
     "1960-05-10": "Visakha Bucha",
-    "1960-05-13": "Royal Ploughing Ceremony",
     "1960-07-01": "Mid-Year Closing Day",
     "1960-07-08": "Asarnha Bucha",
     "1960-07-09": "Buddhist Lent Day",
@@ -201,8 +199,7 @@
     "1961-04-08": "Royal Thai Armed Forces Day",
     "1961-04-13": "Songkran Festival",
     "1961-05-05": "Coronation Day",
-    "1961-05-13": "Royal Ploughing Ceremony",
-    "1961-05-15": "Royal Ploughing Ceremony (in lieu)",
+    "1961-05-11": "Royal Ploughing Ceremony",
     "1961-05-29": "Visakha Bucha",
     "1961-07-01": "Mid-Year Closing Day",
     "1961-07-27": "Asarnha Bucha",
@@ -223,9 +220,7 @@
     "1962-04-08": "Royal Thai Armed Forces Day",
     "1962-04-13": "Songkran Festival",
     "1962-05-05": "Coronation Day",
-    "1962-05-07": "Coronation Day (in lieu)",
-    "1962-05-13": "Royal Ploughing Ceremony",
-    "1962-05-14": "Royal Ploughing Ceremony (in lieu)",
+    "1962-05-07": "Coronation Day (in lieu); Royal Ploughing Ceremony",
     "1962-05-18": "Visakha Bucha",
     "1962-07-01": "Mid-Year Closing Day",
     "1962-07-16": "Asarnha Bucha",
@@ -248,7 +243,7 @@
     "1963-05-05": "Coronation Day",
     "1963-05-06": "Coronation Day (in lieu)",
     "1963-05-07": "Visakha Bucha",
-    "1963-05-13": "Royal Ploughing Ceremony",
+    "1963-05-10": "Royal Ploughing Ceremony",
     "1963-07-01": "Mid-Year Closing Day",
     "1963-07-06": "Asarnha Bucha",
     "1963-07-07": "Buddhist Lent Day",
@@ -268,7 +263,7 @@
     "1964-04-08": "Royal Thai Armed Forces Day",
     "1964-04-13": "Songkran Festival",
     "1964-05-05": "Coronation Day",
-    "1964-05-13": "Royal Ploughing Ceremony",
+    "1964-05-08": "Royal Ploughing Ceremony",
     "1964-05-26": "Visakha Bucha",
     "1964-07-01": "Mid-Year Closing Day",
     "1964-07-24": "Asarnha Bucha",
@@ -338,8 +333,7 @@
     "1967-04-08": "Royal Thai Armed Forces Day",
     "1967-04-13": "Songkran Festival",
     "1967-05-05": "Coronation Day",
-    "1967-05-13": "Royal Ploughing Ceremony",
-    "1967-05-15": "Royal Ploughing Ceremony (in lieu)",
+    "1967-05-11": "Royal Ploughing Ceremony",
     "1967-05-23": "Visakha Bucha",
     "1967-07-01": "Mid-Year Closing Day",
     "1967-07-21": "Asarnha Bucha",
@@ -363,8 +357,9 @@
     "1968-04-15": "Songkran Festival (in lieu)",
     "1968-05-05": "Coronation Day",
     "1968-05-06": "Coronation Day (in lieu)",
+    "1968-05-10": "Royal Ploughing Ceremony",
     "1968-05-11": "Visakha Bucha",
-    "1968-05-13": "Royal Ploughing Ceremony; Visakha Bucha (in lieu)",
+    "1968-05-13": "Visakha Bucha (in lieu)",
     "1968-07-01": "Mid-Year Closing Day",
     "1968-07-09": "Asarnha Bucha",
     "1968-07-10": "Buddhist Lent Day",
@@ -386,7 +381,7 @@
     "1969-04-13": "Songkran Festival",
     "1969-04-14": "Songkran Festival (in lieu)",
     "1969-05-05": "Coronation Day",
-    "1969-05-13": "Royal Ploughing Ceremony",
+    "1969-05-09": "Royal Ploughing Ceremony",
     "1969-05-30": "Visakha Bucha",
     "1969-07-01": "Mid-Year Closing Day",
     "1969-07-28": "Asarnha Bucha",
@@ -406,7 +401,7 @@
     "1970-04-08": "Royal Thai Armed Forces Day",
     "1970-04-13": "Songkran Festival",
     "1970-05-05": "Coronation Day",
-    "1970-05-13": "Royal Ploughing Ceremony",
+    "1970-05-08": "Royal Ploughing Ceremony",
     "1970-05-19": "Visakha Bucha",
     "1970-07-01": "Mid-Year Closing Day",
     "1970-07-18": "Asarnha Bucha",
@@ -428,9 +423,9 @@
     "1971-04-08": "Royal Thai Armed Forces Day",
     "1971-04-13": "Songkran Festival",
     "1971-05-05": "Coronation Day",
+    "1971-05-07": "Royal Ploughing Ceremony",
     "1971-05-09": "Visakha Bucha",
     "1971-05-10": "Visakha Bucha (in lieu)",
-    "1971-05-13": "Royal Ploughing Ceremony",
     "1971-07-01": "Mid-Year Closing Day",
     "1971-07-07": "Asarnha Bucha",
     "1971-07-08": "Buddhist Lent Day",
@@ -452,8 +447,7 @@
     "1972-04-08": "Royal Thai Armed Forces Day",
     "1972-04-13": "Songkran Festival",
     "1972-05-05": "Coronation Day",
-    "1972-05-13": "Royal Ploughing Ceremony",
-    "1972-05-15": "Royal Ploughing Ceremony (in lieu)",
+    "1972-05-08": "Royal Ploughing Ceremony",
     "1972-05-27": "Visakha Bucha",
     "1972-05-29": "Visakha Bucha (in lieu)",
     "1972-07-01": "Mid-Year Closing Day",
@@ -476,9 +470,7 @@
     "1973-04-08": "Royal Thai Armed Forces Day",
     "1973-04-13": "Songkran Festival",
     "1973-05-05": "Coronation Day",
-    "1973-05-07": "Coronation Day (in lieu)",
-    "1973-05-13": "Royal Ploughing Ceremony",
-    "1973-05-14": "Royal Ploughing Ceremony (in lieu)",
+    "1973-05-07": "Coronation Day (in lieu); Royal Ploughing Ceremony",
     "1973-05-16": "Visakha Bucha",
     "1973-07-01": "Mid-Year Closing Day",
     "1973-07-15": "Asarnha Bucha",
@@ -501,7 +493,7 @@
     "1974-05-01": "National Labour Day",
     "1974-05-05": "Coronation Day",
     "1974-05-06": "Visakha Bucha",
-    "1974-05-13": "Royal Ploughing Ceremony",
+    "1974-05-08": "Royal Ploughing Ceremony",
     "1974-07-01": "Mid-Year Closing Day",
     "1974-07-04": "Asarnha Bucha",
     "1974-07-05": "Buddhist Lent Day",
@@ -521,7 +513,7 @@
     "1975-04-13": "Songkran Festival",
     "1975-05-01": "National Labour Day",
     "1975-05-05": "Coronation Day",
-    "1975-05-13": "Royal Ploughing Ceremony",
+    "1975-05-07": "Royal Ploughing Ceremony",
     "1975-05-25": "Visakha Bucha",
     "1975-07-01": "Mid-Year Closing Day",
     "1975-07-23": "Asarnha Bucha",
@@ -542,7 +534,8 @@
     "1976-04-13": "Songkran Festival",
     "1976-05-01": "National Labour Day",
     "1976-05-05": "Coronation Day",
-    "1976-05-13": "Royal Ploughing Ceremony; Visakha Bucha",
+    "1976-05-10": "Royal Ploughing Ceremony",
+    "1976-05-13": "Visakha Bucha",
     "1976-07-01": "Mid-Year Closing Day",
     "1976-07-11": "Asarnha Bucha",
     "1976-07-12": "Buddhist Lent Day",
@@ -563,7 +556,7 @@
     "1977-04-13": "Songkran Festival",
     "1977-05-01": "National Labour Day",
     "1977-05-05": "Coronation Day",
-    "1977-05-13": "Royal Ploughing Ceremony",
+    "1977-05-12": "Royal Ploughing Ceremony",
     "1977-06-01": "Visakha Bucha",
     "1977-07-01": "Mid-Year Closing Day",
     "1977-07-30": "Asarnha Bucha",
@@ -585,7 +578,7 @@
     "1978-04-13": "Songkran Festival",
     "1978-05-01": "National Labour Day",
     "1978-05-05": "Coronation Day",
-    "1978-05-13": "Royal Ploughing Ceremony",
+    "1978-05-11": "Royal Ploughing Ceremony",
     "1978-05-21": "Visakha Bucha",
     "1978-07-01": "Mid-Year Closing Day",
     "1978-07-19": "Asarnha Bucha",
@@ -607,8 +600,8 @@
     "1979-04-13": "Songkran Festival",
     "1979-05-01": "National Labour Day",
     "1979-05-05": "Coronation Day",
+    "1979-05-07": "Royal Ploughing Ceremony",
     "1979-05-10": "Visakha Bucha",
-    "1979-05-13": "Royal Ploughing Ceremony",
     "1979-07-01": "Mid-Year Closing Day",
     "1979-07-09": "Asarnha Bucha",
     "1979-07-10": "Buddhist Lent Day",
@@ -629,7 +622,7 @@
     "1980-04-13": "Songkran Festival",
     "1980-05-01": "National Labour Day",
     "1980-05-05": "Coronation Day",
-    "1980-05-13": "Royal Ploughing Ceremony",
+    "1980-05-14": "Royal Ploughing Ceremony",
     "1980-05-29": "Visakha Bucha",
     "1980-07-01": "Mid-Year Closing Day",
     "1980-07-27": "Asarnha Bucha",
@@ -651,7 +644,7 @@
     "1981-04-13": "Songkran Festival",
     "1981-05-01": "National Labour Day",
     "1981-05-05": "Coronation Day",
-    "1981-05-13": "Royal Ploughing Ceremony",
+    "1981-05-07": "Royal Ploughing Ceremony",
     "1981-05-18": "Visakha Bucha",
     "1981-07-01": "Mid-Year Closing Day",
     "1981-07-16": "Asarnha Bucha",
@@ -674,7 +667,7 @@
     "1982-05-01": "National Labour Day",
     "1982-05-05": "Coronation Day",
     "1982-05-07": "Visakha Bucha",
-    "1982-05-13": "Royal Ploughing Ceremony",
+    "1982-05-19": "Royal Ploughing Ceremony",
     "1982-07-01": "Mid-Year Closing Day",
     "1982-07-05": "Asarnha Bucha",
     "1982-07-06": "Buddhist Lent Day",
@@ -696,7 +689,7 @@
     "1983-04-13": "Songkran Festival",
     "1983-05-01": "National Labour Day",
     "1983-05-05": "Coronation Day",
-    "1983-05-13": "Royal Ploughing Ceremony",
+    "1983-05-11": "Royal Ploughing Ceremony",
     "1983-05-26": "Visakha Bucha",
     "1983-07-01": "Mid-Year Closing Day",
     "1983-07-24": "Asarnha Bucha",
@@ -719,7 +712,7 @@
     "1984-04-13": "Songkran Festival",
     "1984-05-01": "National Labour Day",
     "1984-05-05": "Coronation Day",
-    "1984-05-13": "Royal Ploughing Ceremony",
+    "1984-05-10": "Royal Ploughing Ceremony",
     "1984-05-14": "Visakha Bucha",
     "1984-07-01": "Mid-Year Closing Day",
     "1984-07-12": "Asarnha Bucha",
@@ -743,7 +736,7 @@
     "1985-04-13": "Songkran Festival",
     "1985-05-01": "National Labour Day",
     "1985-05-05": "Coronation Day",
-    "1985-05-13": "Royal Ploughing Ceremony",
+    "1985-05-09": "Royal Ploughing Ceremony",
     "1985-06-02": "Visakha Bucha",
     "1985-07-01": "Mid-Year Closing Day",
     "1985-07-31": "Asarnha Bucha",
@@ -767,7 +760,7 @@
     "1986-04-13": "Songkran Festival",
     "1986-05-01": "National Labour Day",
     "1986-05-05": "Coronation Day",
-    "1986-05-13": "Royal Ploughing Ceremony",
+    "1986-05-09": "Royal Ploughing Ceremony",
     "1986-05-22": "Visakha Bucha",
     "1986-07-01": "Mid-Year Closing Day",
     "1986-07-20": "Asarnha Bucha",
@@ -791,8 +784,8 @@
     "1987-04-13": "Songkran Festival",
     "1987-05-01": "National Labour Day",
     "1987-05-05": "Coronation Day",
+    "1987-05-08": "Royal Ploughing Ceremony",
     "1987-05-11": "Visakha Bucha",
-    "1987-05-13": "Royal Ploughing Ceremony",
     "1987-07-01": "Mid-Year Closing Day",
     "1987-07-10": "Asarnha Bucha",
     "1987-07-11": "Buddhist Lent Day",
@@ -815,7 +808,7 @@
     "1988-04-13": "Songkran Festival",
     "1988-05-01": "National Labour Day",
     "1988-05-05": "Coronation Day",
-    "1988-05-13": "Royal Ploughing Ceremony",
+    "1988-05-11": "Royal Ploughing Ceremony",
     "1988-05-30": "Visakha Bucha",
     "1988-07-01": "Mid-Year Closing Day",
     "1988-07-28": "Asarnha Bucha",
@@ -842,7 +835,7 @@
     "1989-04-14": "Songkran Festival",
     "1989-05-01": "National Labour Day",
     "1989-05-05": "Coronation Day",
-    "1989-05-13": "Royal Ploughing Ceremony",
+    "1989-05-11": "Royal Ploughing Ceremony",
     "1989-05-19": "Visakha Bucha",
     "1989-07-01": "Mid-Year Closing Day",
     "1989-07-17": "Asarnha Bucha",
@@ -872,7 +865,7 @@
     "1990-05-01": "National Labour Day",
     "1990-05-05": "Coronation Day",
     "1990-05-08": "Visakha Bucha",
-    "1990-05-13": "Royal Ploughing Ceremony",
+    "1990-05-11": "Royal Ploughing Ceremony",
     "1990-07-01": "Mid-Year Closing Day",
     "1990-07-07": "Asarnha Bucha",
     "1990-07-08": "Buddhist Lent Day",
@@ -900,7 +893,7 @@
     "1991-04-14": "Songkran Festival",
     "1991-05-01": "National Labour Day",
     "1991-05-05": "Coronation Day",
-    "1991-05-13": "Royal Ploughing Ceremony",
+    "1991-05-10": "Royal Ploughing Ceremony",
     "1991-05-28": "Visakha Bucha",
     "1991-07-01": "Mid-Year Closing Day",
     "1991-07-26": "Asarnha Bucha",
@@ -929,7 +922,7 @@
     "1992-04-14": "Songkran Festival",
     "1992-05-01": "National Labour Day",
     "1992-05-05": "Coronation Day",
-    "1992-05-13": "Royal Ploughing Ceremony",
+    "1992-05-14": "Royal Ploughing Ceremony",
     "1992-05-16": "Visakha Bucha",
     "1992-05-18": "Special In Lieu Holiday",
     "1992-07-01": "Mid-Year Closing Day",
@@ -961,7 +954,7 @@
     "1993-05-01": "National Labour Day",
     "1993-05-03": "Special In Lieu Holiday",
     "1993-05-05": "Coronation Day; Visakha Bucha",
-    "1993-05-13": "Royal Ploughing Ceremony",
+    "1993-05-17": "Royal Ploughing Ceremony",
     "1993-07-01": "Mid-Year Closing Day",
     "1993-07-03": "Asarnha Bucha",
     "1993-07-04": "Buddhist Lent Day",
@@ -993,7 +986,7 @@
     "1994-05-01": "National Labour Day",
     "1994-05-02": "Special In Lieu Holiday",
     "1994-05-05": "Coronation Day",
-    "1994-05-13": "Royal Ploughing Ceremony",
+    "1994-05-11": "Royal Ploughing Ceremony",
     "1994-05-24": "Visakha Bucha",
     "1994-07-01": "Mid-Year Closing Day",
     "1994-07-22": "Asarnha Bucha",
@@ -1027,8 +1020,9 @@
     "1995-04-14": "Songkran Festival",
     "1995-05-01": "National Labour Day",
     "1995-05-05": "Coronation Day",
-    "1995-05-13": "Royal Ploughing Ceremony; Visakha Bucha",
-    "1995-05-15": "Royal Ploughing Ceremony (in lieu); Visakha Bucha (in lieu)",
+    "1995-05-10": "Royal Ploughing Ceremony",
+    "1995-05-13": "Visakha Bucha",
+    "1995-05-15": "Visakha Bucha (in lieu)",
     "1995-07-01": "Mid-Year Closing Day",
     "1995-07-11": "Asarnha Bucha",
     "1995-07-12": "Buddhist Lent Day",
@@ -1063,7 +1057,7 @@
     "1996-05-01": "National Labour Day",
     "1996-05-05": "Coronation Day",
     "1996-05-06": "Coronation Day (in lieu)",
-    "1996-05-13": "Royal Ploughing Ceremony",
+    "1996-05-16": "Royal Ploughing Ceremony",
     "1996-05-31": "Visakha Bucha",
     "1996-06-10": "HM King Bhumibol Adulyadej's Golden Jubilee",
     "1996-07-01": "Mid-Year Closing Day",
@@ -1096,7 +1090,7 @@
     "1997-04-15": "Songkran Festival (in lieu)",
     "1997-05-01": "National Labour Day",
     "1997-05-05": "Coronation Day",
-    "1997-05-13": "Royal Ploughing Ceremony",
+    "1997-05-09": "Royal Ploughing Ceremony",
     "1997-05-20": "Visakha Bucha",
     "1997-07-01": "Mid-Year Closing Day",
     "1997-07-19": "Asarnha Bucha",
@@ -1127,9 +1121,9 @@
     "1998-04-15": "Songkran Festival",
     "1998-05-01": "National Labour Day",
     "1998-05-05": "Coronation Day",
+    "1998-05-08": "Royal Ploughing Ceremony",
     "1998-05-10": "Visakha Bucha",
     "1998-05-11": "Special In Lieu Holiday",
-    "1998-05-13": "Royal Ploughing Ceremony",
     "1998-07-01": "Mid-Year Closing Day",
     "1998-07-08": "Asarnha Bucha",
     "1998-07-09": "Buddhist Lent Day",
@@ -1160,6 +1154,7 @@
     "1999-05-01": "National Labour Day",
     "1999-05-03": "Special In Lieu Holiday",
     "1999-05-05": "Coronation Day",
+    "1999-05-14": "Royal Ploughing Ceremony",
     "1999-05-29": "Visakha Bucha",
     "1999-05-31": "Special In Lieu Holiday",
     "1999-07-01": "Mid-Year Closing Day",
@@ -1538,7 +1533,7 @@
     "2010-05-01": "National Labour Day",
     "2010-05-03": "National Labour Day (in lieu)",
     "2010-05-05": "Coronation Day",
-    "2010-05-10": "Royal Ploughing Ceremony",
+    "2010-05-13": "Royal Ploughing Ceremony",
     "2010-05-20": "Bridge Public Holiday",
     "2010-05-21": "Bridge Public Holiday",
     "2010-05-28": "Visakha Bucha",
@@ -1938,7 +1933,7 @@
     "2021-05-01": "National Labour Day",
     "2021-05-03": "National Labour Day (in lieu)",
     "2021-05-04": "Coronation Day",
-    "2021-05-13": "Royal Ploughing Ceremony",
+    "2021-05-10": "Royal Ploughing Ceremony",
     "2021-05-26": "Visakha Bucha",
     "2021-06-03": "HM Queen Suthida's Birthday",
     "2021-07-24": "Asarnha Bucha",
@@ -1976,9 +1971,9 @@
     "2022-05-01": "National Labour Day",
     "2022-05-02": "National Labour Day (in lieu)",
     "2022-05-04": "Coronation Day",
+    "2022-05-13": "Royal Ploughing Ceremony",
     "2022-05-15": "Visakha Bucha",
     "2022-05-16": "Visakha Bucha (in lieu)",
-    "2022-05-17": "Royal Ploughing Ceremony",
     "2022-06-03": "HM Queen Suthida's Birthday",
     "2022-07-13": "Asarnha Bucha",
     "2022-07-14": "Buddhist Lent Day",
@@ -2018,7 +2013,7 @@
     "2023-05-01": "National Labour Day",
     "2023-05-04": "Coronation Day",
     "2023-05-05": "Bridge Public Holiday",
-    "2023-05-11": "Royal Ploughing Ceremony",
+    "2023-05-17": "Royal Ploughing Ceremony",
     "2023-06-03": "HM Queen Suthida's Birthday; Visakha Bucha",
     "2023-06-05": "HM Queen Suthida's Birthday (in lieu); Visakha Bucha (in lieu)",
     "2023-07-28": "HM King Maha Vajiralongkorn's Birthday",
@@ -2056,6 +2051,7 @@
     "2024-05-01": "National Labour Day",
     "2024-05-04": "Coronation Day",
     "2024-05-06": "Coronation Day (in lieu)",
+    "2024-05-10": "Royal Ploughing Ceremony",
     "2024-05-22": "Visakha Bucha",
     "2024-06-03": "HM Queen Suthida's Birthday",
     "2024-07-20": "Asarnha Bucha",
@@ -2072,6 +2068,7 @@
     "2024-11-15": "Loy Krathong",
     "2024-12-05": "HM King Bhumibol Adulyadej the Great's Birthday; National Day; National Father's Day",
     "2024-12-10": "Constitution Day",
+    "2024-12-30": "Bridge Public Holiday",
     "2024-12-31": "New Year's Eve",
     "2025-01-01": "New Year's Day",
     "2025-01-11": "National Children's Day",
diff --git a/tests/countries/test_thailand.py b/tests/countries/test_thailand.py
index 2a58a9760..929541269 100644
--- a/tests/countries/test_thailand.py
+++ b/tests/countries/test_thailand.py
@@ -103,6 +103,7 @@ def test_special_holidays(self):
             "2023-05-05",
             "2023-07-31",
             "2023-12-29",
+            "2024-12-30",
         )
         dt_observed = (
             "2007-12-24",
@@ -135,9 +136,9 @@ def test_2022_all(self):
             ("2022-05-01", "วันแรงงานแห่งชาติ"),
             ("2022-05-02", "ชดเชยวันแรงงานแห่งชาติ"),
             ("2022-05-04", "วันฉัตรมงคล"),
+            ("2022-05-13", "วันพืชมงคล"),
             ("2022-05-15", "วันวิสาขบูชา"),
             ("2022-05-16", "ชดเชยวันวิสาขบูชา"),
-            ("2022-05-17", "วันพืชมงคล"),
             (
                 "2022-06-03",
                 "วันเฉลิมพระชนมพรรษาสมเด็จพระนางเจ้าสุทิดา พัชรสุธาพิมลลักษณ พระบรมราชินี",
@@ -613,9 +614,47 @@ def test_khao_phansa(self):
     def test_raeknakhwan(self):
         name = "วันพืชมงคล"
         self.assertHolidays(
-            Thailand(categories=GOVERNMENT, years=range(1997, 2024)),
-            ("1997-05-13", name),
-            ("1998-05-13", name),
+            Thailand(categories=GOVERNMENT, years=range(1960, 2024)),
+            ("1960-05-02", name),
+            ("1961-05-11", name),
+            ("1962-05-07", name),
+            ("1963-05-10", name),
+            ("1964-05-08", name),
+            ("1965-05-13", name),
+            ("1966-05-13", name),
+            ("1967-05-11", name),
+            ("1968-05-10", name),
+            ("1969-05-09", name),
+            ("1970-05-08", name),
+            ("1971-05-07", name),
+            ("1972-05-08", name),
+            ("1973-05-07", name),
+            ("1974-05-08", name),
+            ("1975-05-07", name),
+            ("1976-05-10", name),
+            ("1977-05-12", name),
+            ("1978-05-11", name),
+            ("1979-05-07", name),
+            ("1980-05-14", name),
+            ("1981-05-07", name),
+            ("1982-05-19", name),
+            ("1983-05-11", name),
+            ("1984-05-10", name),
+            ("1985-05-09", name),
+            ("1986-05-09", name),
+            ("1987-05-08", name),
+            ("1988-05-11", name),
+            ("1989-05-11", name),
+            ("1990-05-11", name),
+            ("1991-05-10", name),
+            ("1992-05-14", name),
+            ("1993-05-17", name),
+            ("1994-05-11", name),
+            ("1995-05-10", name),
+            ("1996-05-16", name),
+            ("1997-05-09", name),
+            ("1998-05-08", name),
+            # Not a holiday in 1999 date, was held on MAY, 14.
             ("2000-05-15", name),
             ("2001-05-16", name),
             ("2002-05-09", name),
@@ -626,7 +665,7 @@ def test_raeknakhwan(self):
             ("2007-05-10", name),
             ("2008-05-09", name),
             ("2009-05-11", name),
-            ("2010-05-10", name),
+            ("2010-05-13", name),
             ("2011-05-13", name),
             ("2012-05-09", name),
             ("2013-05-13", name),
@@ -637,9 +676,10 @@ def test_raeknakhwan(self):
             ("2018-05-14", name),
             ("2019-05-09", name),
             ("2020-05-11", name),
-            ("2021-05-13", name),
-            ("2022-05-17", name),
-            ("2023-05-11", name),
+            ("2021-05-10", name),
+            ("2022-05-13", name),
+            ("2023-05-17", name),
+            ("2024-05-10", name),
         )
 
     def test_armed_forces_holiday(self):
@@ -751,6 +791,20 @@ def test_workday_1995(self):
             ("1995-11-06", "วันลอยกระทง"),
         )
 
+    def test_workday_1999(self):
+        self.assertHolidays(
+            Thailand(categories=WORKDAY, years=1999),
+            ("1999-01-13", "วันการบินแห่งชาติ"),
+            ("1999-01-14", "วันอนุรักษ์ทรัพยากรป่าไม้ของชาติ"),
+            ("1999-01-17", "วันพ่อขุนรามคำแหงมหาราช"),
+            ("1999-02-03", "วันทหารผ่านศึก"),
+            ("1999-02-26", "วันศิลปินแห่งชาติ"),
+            ("1999-03-08", "วันสตรีสากล"),
+            ("1999-05-14", "วันพืชมงคล"),
+            ("1999-08-18", "วันวิทยาศาสตร์แห่งชาติ"),
+            ("1999-11-22", "วันลอยกระทง"),
+        )
+
     def test_workday_2017(self):
         self.assertHolidays(
             Thailand(categories=WORKDAY, years=2017),
@@ -786,9 +840,9 @@ def test_l10n_default(self):
             ("2022-05-01", "วันแรงงานแห่งชาติ"),
             ("2022-05-02", "ชดเชยวันแรงงานแห่งชาติ"),
             ("2022-05-04", "วันฉัตรมงคล"),
+            ("2022-05-13", "วันพืชมงคล"),
             ("2022-05-15", "วันวิสาขบูชา"),
             ("2022-05-16", "ชดเชยวันวิสาขบูชา"),
-            ("2022-05-17", "วันพืชมงคล"),
             (
                 "2022-06-03",
                 "วันเฉลิมพระชนมพรรษาสมเด็จพระนางเจ้าสุทิดา พัชรสุธาพิมลลักษณ พระบรมราชินี",
@@ -853,9 +907,9 @@ def test_l10n_en_US(self):
             ("2022-05-01", "National Labour Day"),
             ("2022-05-02", "National Labour Day (in lieu)"),
             ("2022-05-04", "Coronation Day"),
+            ("2022-05-13", "Royal Ploughing Ceremony"),
             ("2022-05-15", "Visakha Bucha"),
             ("2022-05-16", "Visakha Bucha (in lieu)"),
-            ("2022-05-17", "Royal Ploughing Ceremony"),
             ("2022-06-03", "HM Queen Suthida's Birthday"),
             ("2022-07-13", "Asarnha Bucha"),
             ("2022-07-14", "Buddhist Lent Day"),