diff --git a/package.json b/package.json
index 719068ac87d..1529252086c 100644
--- a/package.json
+++ b/package.json
@@ -46,7 +46,7 @@
     "@mui/styled-engine-sc": "^5.14.12",
     "@mui/styles": "^5.15.15",
     "@reduxjs/toolkit": "^1.9.3",
-    "@terraware/web-components": "^3.4.3",
+    "@terraware/web-components": "^3.4.4",
     "@testing-library/jest-dom": "^6.0.0",
     "@testing-library/react": "^14.3.0",
     "@testing-library/user-event": "^14.4.3",
diff --git a/src/api/types/generated-schema.ts b/src/api/types/generated-schema.ts
index f21b2770210..a2a5bd74b65 100644
--- a/src/api/types/generated-schema.ts
+++ b/src/api/types/generated-schema.ts
@@ -3720,6 +3720,10 @@ export interface components {
        */
       mortalityRate?: number;
       notes?: string;
+      /** @description IDs of any newer monitoring plots that overlap with this one. */
+      overlappedByPlotIds: number[];
+      /** @description IDs of any older monitoring plots this one overlaps with. */
+      overlapsWithPlotIds: number[];
       photos: components["schemas"]["ObservationMonitoringPlotPhotoPayload"][];
       /**
        * Format: int32
diff --git a/src/redux/features/observations/utils.ts b/src/redux/features/observations/utils.ts
index ba598b2f557..7a5f011f8be 100644
--- a/src/redux/features/observations/utils.ts
+++ b/src/redux/features/observations/utils.ts
@@ -270,3 +270,11 @@ const mergeSpecies = (
       })
     );
 };
+
+export const has25mPlots = (
+  subzones: ObservationPlantingSubzoneResults[] | ObservationPlantingSubzoneResultsPayload[]
+) => {
+  return subzones
+    ?.flatMap((subzone: { monitoringPlots: any[] }) => subzone.monitoringPlots.flatMap((plot) => plot.sizeMeters))
+    .some((size: number) => size.toString() === '25');
+};
diff --git a/src/scenes/ObservationsRouter/details/ObservationDetailsRenderer.tsx b/src/scenes/ObservationsRouter/details/ObservationDetailsRenderer.tsx
index 3aa65c94c97..14174d4a805 100644
--- a/src/scenes/ObservationsRouter/details/ObservationDetailsRenderer.tsx
+++ b/src/scenes/ObservationsRouter/details/ObservationDetailsRenderer.tsx
@@ -4,6 +4,7 @@ import Link from 'src/components/common/Link';
 import CellRenderer, { TableRowType } from 'src/components/common/table/TableCellRenderer';
 import { RendererProps } from 'src/components/common/table/types';
 import { APP_PATHS } from 'src/constants';
+import { has25mPlots } from 'src/redux/features/observations/utils';
 import { MonitoringPlotStatus, getPlotStatus } from 'src/types/Observations';
 
 const NO_DATA_FIELDS = ['totalPlants', 'totalSpecies', 'mortalityRate'];
@@ -21,6 +22,7 @@ const ObservationDetailsRenderer =
       return (
         <Link fontSize='16px' to={url}>
           {name as React.ReactNode}
+          {has25mPlots(row.plantingSubzones) ? '*' : ''}
         </Link>
       );
     };
diff --git a/src/scenes/ObservationsRouter/details/index.tsx b/src/scenes/ObservationsRouter/details/index.tsx
index 89c41d26615..381438af6b3 100644
--- a/src/scenes/ObservationsRouter/details/index.tsx
+++ b/src/scenes/ObservationsRouter/details/index.tsx
@@ -14,6 +14,7 @@ import {
   selectDetailsZoneNames,
 } from 'src/redux/features/observations/observationDetailsSelectors';
 import { selectObservation } from 'src/redux/features/observations/observationsSelectors';
+import { has25mPlots } from 'src/redux/features/observations/utils';
 import { selectPlantingSite } from 'src/redux/features/tracking/trackingSelectors';
 import { useAppSelector } from 'src/redux/store';
 import AggregatedPlantsStats from 'src/scenes/ObservationsRouter/common/AggregatedPlantsStats';
@@ -134,6 +135,13 @@ export default function ObservationDetails(props: ObservationDetailsProps): JSX.
     }
   }, [zoneNames, searchProps.filtersProps]);
 
+  const has25mPlotsZones = () => {
+    const allSubzones = details?.plantingZones.flatMap((zone) => zone.plantingSubzones.flatMap((subzone) => subzone));
+    if (allSubzones) {
+      return has25mPlots(allSubzones);
+    }
+  };
+
   return (
     <DetailsPage title={title} plantingSiteId={plantingSiteId}>
       <ObservationStatusSummaryMessage
@@ -155,6 +163,7 @@ export default function ObservationDetails(props: ObservationDetailsProps): JSX.
                 rows={details?.plantingZones ?? []}
                 orderBy='plantingZoneName'
                 Renderer={ObservationDetailsRenderer(plantingSiteId, observationId)}
+                tableComments={has25mPlotsZones() ? strings.PLOTS_SIZE_NOTE : undefined}
               />
             </Box>
           </Card>
diff --git a/src/scenes/ObservationsRouter/plot/index.tsx b/src/scenes/ObservationsRouter/plot/index.tsx
index 5452e181198..c499d165846 100644
--- a/src/scenes/ObservationsRouter/plot/index.tsx
+++ b/src/scenes/ObservationsRouter/plot/index.tsx
@@ -5,8 +5,10 @@ import { Box, Grid, Typography, useTheme } from '@mui/material';
 import { Textfield } from '@terraware/web-components';
 
 import Card from 'src/components/common/Card';
+import Link from 'src/components/common/Link';
 import { APP_PATHS } from 'src/constants';
 import { useLocalization } from 'src/providers';
+import { searchObservationDetails } from 'src/redux/features/observations/observationDetailsSelectors';
 import { selectObservationMonitoringPlot } from 'src/redux/features/observations/observationMonitoringPlotSelectors';
 import { selectPlantingSite } from 'src/redux/features/tracking/trackingSelectors';
 import { useAppSelector } from 'src/redux/store';
@@ -48,6 +50,19 @@ export default function ObservationMonitoringPlot(): JSX.Element {
 
   const plantingSite = useAppSelector((state) => selectPlantingSite(state, Number(plantingSiteId)));
 
+  const details = useAppSelector((state) =>
+    searchObservationDetails(
+      state,
+      {
+        plantingSiteId: Number(plantingSiteId),
+        observationId: Number(observationId),
+        search: '',
+        zoneNames: [],
+      },
+      defaultTimeZone.get().id
+    )
+  );
+
   const gridSize = isMobile ? 12 : 4;
 
   const data: Record<string, any>[] = useMemo(() => {
@@ -105,6 +120,38 @@ export default function ObservationMonitoringPlot(): JSX.Element {
     }
   }, [navigate, monitoringPlot, observationId, plantingZoneId, plantingSiteId]);
 
+  const getReplacedPlotsNames = (): JSX.Element[] => {
+    const names =
+      monitoringPlot?.overlapsWithPlotIds.map((plotId, index) => {
+        const allPlots = details?.plantingZones?.flatMap((pz) =>
+          pz.plantingSubzones.flatMap((subzone) => subzone.monitoringPlots.flatMap((plot) => plot))
+        );
+        const found = allPlots?.find((plot) => plot.monitoringPlotId === plotId);
+        if (found) {
+          return (
+            <Link
+              key={`plot-link-${index}`}
+              to={APP_PATHS.OBSERVATION_MONITORING_PLOT_DETAILS.replace(
+                ':plantingSiteId',
+                Number(plantingSiteId).toString()
+              )
+                .replace(':observationId', Number(observationId).toString())
+                .replace(
+                  ':plantingZoneId',
+                  Number(plantingZoneId).toString().replace(':monitoringPlotId', found.monitoringPlotId.toString())
+                )}
+            >
+              {found.monitoringPlotName}
+            </Link>
+          );
+        }
+        return undefined;
+      }) || [];
+
+    const elements = (names ?? []).filter((element): element is JSX.Element => element !== undefined);
+    return elements;
+  };
+
   return (
     <DetailsPage
       title={monitoringPlot?.monitoringPlotName ?? ''}
@@ -129,6 +176,14 @@ export default function ObservationMonitoringPlot(): JSX.Element {
                   />
                 </Grid>
               ))}
+              {monitoringPlot?.overlapsWithPlotIds && monitoringPlot.overlapsWithPlotIds.length > 0 && (
+                <Grid item xs={gridSize} marginTop={2}>
+                  <Typography fontSize='14px' fontWeight={400} color={theme.palette.TwClrTxtSecondary}>
+                    {strings.PLOT_REPLACES_THIS_25M_PLOT}
+                  </Typography>
+                  {getReplacedPlotsNames()}
+                </Grid>
+              )}
             </Grid>
             {title(strings.NUMBER_OF_LIVE_PLANTS_PER_SPECIES)}
             <Box height='360px'>
diff --git a/src/scenes/ObservationsRouter/schedule/ObservationSubzoneSelector.tsx b/src/scenes/ObservationsRouter/schedule/ObservationSubzoneSelector.tsx
index 8d544d44dcb..539c0fa6f7b 100644
--- a/src/scenes/ObservationsRouter/schedule/ObservationSubzoneSelector.tsx
+++ b/src/scenes/ObservationsRouter/schedule/ObservationSubzoneSelector.tsx
@@ -1,10 +1,14 @@
-import React, { useEffect, useState } from 'react';
+import React, { useCallback, useEffect, useState } from 'react';
 
-import { Box, Grid, useTheme } from '@mui/material';
+import { Box, Grid, Typography, useTheme } from '@mui/material';
 import { Checkbox } from '@terraware/web-components';
 
+import { selectObservations, selectObservationsResults } from 'src/redux/features/observations/observationsSelectors';
+import { useAppSelector } from 'src/redux/store';
 import strings from 'src/strings';
+import { ObservationResultsPayload } from 'src/types/Observations';
 import { PlantingSiteWithReportedPlants, PlantingZone } from 'src/types/Tracking';
+import { isAfter } from 'src/utils/dateUtils';
 
 interface ObservationSubzoneSelectorProps {
   onChangeSelectedSubzones: (requestedSubzoneIds: number[]) => void;
@@ -15,6 +19,58 @@ const ObservationSubzoneSelector = ({ onChangeSelectedSubzones, plantingSite }:
   const theme = useTheme();
 
   const [selectedSubzones, setSelectedSubzones] = useState(new Map<number, boolean>());
+  const observationsData = useAppSelector(selectObservations);
+
+  const allObservationsResults = useAppSelector(selectObservationsResults);
+  const plantingSiteObservations = allObservationsResults?.filter(
+    (observation) => observation.plantingSiteId === plantingSite.id
+  );
+  const zoneObservations: ObservationResultsPayload[][] = [];
+  plantingSiteObservations?.forEach((observation) => {
+    observation.plantingZones.forEach((pz) => {
+      zoneObservations[pz.plantingZoneId]
+        ? zoneObservations[pz.plantingZoneId].push(observation)
+        : (zoneObservations[pz.plantingZoneId] = [observation]);
+    });
+  });
+
+  const lastZoneObservation = (observationsList: ObservationResultsPayload[]) => {
+    const observationsToProcess = observationsList;
+    if (observationsToProcess && observationsToProcess.length > 0) {
+      let lastObs = observationsToProcess[0];
+      observationsToProcess.forEach((obs) => {
+        if (isAfter(obs.startDate, lastObs.startDate)) {
+          lastObs = obs;
+        }
+      });
+      return lastObs;
+    }
+  };
+
+  const lastSubZoneObservation = useCallback(
+    (
+      zoneId: number,
+      subzoneId: number,
+      observationsList?: ObservationResultsPayload[]
+    ): ObservationResultsPayload | undefined => {
+      const observationsToProcess = observationsList ? observationsList : zoneObservations?.[zoneId];
+      const lastZoneObs = lastZoneObservation(observationsToProcess);
+      const foundObs = observationsData?.find((ob) => ob.id === lastZoneObs?.observationId);
+
+      if (foundObs) {
+        if (!foundObs.requestedSubzoneIds || foundObs.requestedSubzoneIds.includes(subzoneId)) {
+          return lastZoneObs;
+        } else {
+          const newZoneObservations = observationsToProcess.filter(
+            (ob) => ob.observationId !== lastZoneObs?.observationId
+          );
+
+          return lastSubZoneObservation(zoneId, subzoneId, newZoneObservations);
+        }
+      }
+    },
+    [zoneObservations, observationsData]
+  );
 
   useEffect(() => {
     // Initialize all subzone selections with subzoneId -> false unless they have totalPlants > 0
@@ -63,32 +119,66 @@ const ObservationSubzoneSelector = ({ onChangeSelectedSubzones, plantingSite }:
 
   return (
     <Grid container spacing={3}>
-      {plantingSite.plantingZones?.map((zone, index) => (
-        <Grid item xs={12} key={index}>
-          <Checkbox
-            id={`observation-zone-${zone.id}`}
-            indeterminate={isZonePartiallySelected(zone)}
-            label={zone.name}
-            name='Limit Observation to Zone'
-            onChange={(value) => onChangeZoneCheckbox(zone, value)}
-            value={isZoneFullySelected(zone)}
-          />
-
-          <Box sx={{ columnCount: 2, columnGap: theme.spacing(3), paddingLeft: `${theme.spacing(4)}` }}>
-            {zone.plantingSubzones.map((subzone, _index) => (
-              <Box sx={{ display: 'inline-block', width: '100%' }} key={_index}>
-                <Checkbox
-                  id={`observation-subzone-${zone.id}`}
-                  label={subzone.totalPlants ? subzone.name : <Box>⚠️ {subzone.name}</Box>}
-                  name='Limit Observation to Subzone'
-                  onChange={(value) => onChangeSubzoneCheckbox(subzone.id, value)}
-                  value={selectedSubzones.get(subzone.id)}
-                />
-              </Box>
-            ))}
-          </Box>
-        </Grid>
-      ))}
+      {plantingSite.plantingZones?.map((zone, index) => {
+        const lastZoneOb = lastZoneObservation(zoneObservations?.[zone.id]);
+        return (
+          <Grid item xs={12} key={index}>
+            <Checkbox
+              id={`observation-zone-${zone.id}`}
+              indeterminate={isZonePartiallySelected(zone)}
+              label={zone.name}
+              name='Limit Observation to Zone'
+              onChange={(value) => onChangeZoneCheckbox(zone, value)}
+              value={isZoneFullySelected(zone)}
+            />
+            <Typography
+              sx={{
+                display: 'inline',
+                fontWeight: 500,
+                color: theme.palette.TwClrTxtSecondary,
+                verticalAlign: 'bottom',
+                paddingLeft: 1,
+              }}
+            >
+              {lastZoneOb
+                ? strings.formatString(strings.LAST_OBSERVATION, lastZoneOb.startDate || '')
+                : strings.NO_OBSERVATIONS_HAVE_BEEN_SCHEDULED}
+            </Typography>
+
+            <Box sx={{ columnGap: theme.spacing(3), paddingLeft: `${theme.spacing(4)}` }}>
+              {zone.plantingSubzones.map((subzone, _index) => {
+                const lastSubzoneOb = lastSubZoneObservation(zone.id, subzone.id);
+                return (
+                  <Box sx={{ display: 'inline-block', width: '100%' }} key={_index}>
+                    <Checkbox
+                      id={`observation-subzone-${zone.id}`}
+                      label={subzone.totalPlants ? subzone.name : <Box>⚠️ {subzone.name}</Box>}
+                      name='Limit Observation to Subzone'
+                      onChange={(value) => onChangeSubzoneCheckbox(subzone.id, value)}
+                      value={selectedSubzones.get(subzone.id)}
+                    />
+                    {lastZoneOb && (
+                      <Typography
+                        sx={{
+                          display: 'inline',
+                          fontWeight: 500,
+                          color: theme.palette.TwClrTxtSecondary,
+                          verticalAlign: 'bottom',
+                          paddingLeft: 1,
+                        }}
+                      >
+                        {lastSubzoneOb
+                          ? strings.formatString(strings.LAST_OBSERVATION, lastSubzoneOb.startDate || '')
+                          : strings.NO_OBSERVATIONS_HAVE_BEEN_SCHEDULED}
+                      </Typography>
+                    )}
+                  </Box>
+                );
+              })}
+            </Box>
+          </Grid>
+        );
+      })}
       <Grid item xs={12}>
         <Box>⚠️: {strings.NO_PLANTS}</Box>
       </Grid>
diff --git a/src/scenes/ObservationsRouter/zone/ObservationPlantingZoneRenderer.tsx b/src/scenes/ObservationsRouter/zone/ObservationPlantingZoneRenderer.tsx
index 00f000cf1ac..068e9745556 100644
--- a/src/scenes/ObservationsRouter/zone/ObservationPlantingZoneRenderer.tsx
+++ b/src/scenes/ObservationsRouter/zone/ObservationPlantingZoneRenderer.tsx
@@ -29,6 +29,7 @@ const ObservationPlantingZoneRenderer =
       return (
         <Link fontSize='16px' to={url}>
           {name as React.ReactNode}
+          {row.sizeMeters.toString() === '25' ? '*' : ''}
         </Link>
       );
     };
diff --git a/src/scenes/ObservationsRouter/zone/index.tsx b/src/scenes/ObservationsRouter/zone/index.tsx
index 4732991b5a5..0e6eb85e228 100644
--- a/src/scenes/ObservationsRouter/zone/index.tsx
+++ b/src/scenes/ObservationsRouter/zone/index.tsx
@@ -11,6 +11,7 @@ import Table from 'src/components/common/table';
 import { APP_PATHS } from 'src/constants';
 import { useLocalization, useOrganization } from 'src/providers';
 import { searchObservationPlantingZone } from 'src/redux/features/observations/observationPlantingZoneSelectors';
+import { has25mPlots } from 'src/redux/features/observations/utils';
 import { selectPlantingSite } from 'src/redux/features/tracking/trackingSelectors';
 import { useAppSelector } from 'src/redux/store';
 import AggregatedPlantsStats from 'src/scenes/ObservationsRouter/common/AggregatedPlantsStats';
@@ -184,6 +185,11 @@ export default function ObservationPlantingZone(): JSX.Element {
                   plantingZoneId,
                   setReplaceObservationPlot
                 )}
+                tableComments={
+                  plantingZone?.plantingSubzones && has25mPlots(plantingZone.plantingSubzones)
+                    ? strings.PLOTS_SIZE_NOTE
+                    : undefined
+                }
               />
             </Box>
           </Card>
diff --git a/src/strings/csv/en.csv b/src/strings/csv/en.csv
index b937dc8bd93..44ec5b96141 100644
--- a/src/strings/csv/en.csv
+++ b/src/strings/csv/en.csv
@@ -752,6 +752,7 @@ LAST_EDITED_BY,Last Edited By,
 LAST_MODIFIED_BY,Last modified by,
 LAST_MODIFIED_ON,Last modified on,
 LAST_NAME,Last Name,
+LAST_OBSERVATION,Last Observation: {0},
 LAST_OBSERVED,Last Observed,
 LAST_UPDATED,Last Updated,
 LATITUDE_LONGITUDE,"Latitude, Longitude",
@@ -930,6 +931,7 @@ NO_LOCATION_FOUND,Location not found,
 NO_MAP_DATA,No map data to show for this planting site.,
 NO_NOTIFICATIONS,No notifications to show.,
 NO_NURSERIES_NON_ADMIN_MSG,"Before you can add and manage your nursery inventory, you’ll need to have a nursery and species within Terraware. Only admins can add nurseries and species, so please reach out to yours for assistance.",
+NO_OBSERVATIONS_HAVE_BEEN_SCHEDULED,No observations have been scheduled,
 NO_PARTICIPANT,No Participant,
 NO_PLANTING_SITES_DESCRIPTION,Start by adding a planting site. Adding a planting site will allow you to track where seedlings go after they leave the nursery.,
 NO_PLANTING_SITES_TITLE,"Just a moment, let’s add a planting site first.",
@@ -1195,8 +1197,10 @@ PLANTS,Plants,
 PLANTS_CARD_DESCRIPTION,They’ve taken root! View all your plants in one place.,
 PLANTS_PER_HECTARE,plants/ha,
 PLEASE_TRY_AGAIN,Please try again.,
+PLOT_REPLACES_THIS_25M_PLOT,Plot replaces this 25x25m plot:
 PLOT_TYPE,Plot Type,
 PLOTS_PERMANENT,Permanent Plots,
+PLOTS_SIZE_NOTE,*Data collected with 25x25m plots,
 PLOTS_TEMPORARY,Temporary Plots,
 POSITION,Position,
 POUNDS,Pounds,
diff --git a/yarn.lock b/yarn.lock
index 4c11523b9a8..50fb850afb2 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -3998,10 +3998,10 @@
   dependencies:
     defer-to-connect "^2.0.1"
 
-"@terraware/web-components@^3.4.3":
-  version "3.4.3"
-  resolved "https://registry.yarnpkg.com/@terraware/web-components/-/web-components-3.4.3.tgz#1027b0bddbd502eafe209191a3fdfe86030ed886"
-  integrity sha512-UhXXLt9p2piN05y7ritNG5HADryPGg7dJ3oUwKyPcZEEJYKY5Ze+w0TRu3gP8WhlVUlzYzDc0Xrg7eVct89Qxg==
+"@terraware/web-components@^3.4.4":
+  version "3.4.4"
+  resolved "https://registry.yarnpkg.com/@terraware/web-components/-/web-components-3.4.4.tgz#d58ee7ad87f9c766618ca78a9b5b32e40d0c8602"
+  integrity sha512-9PvOr6Phl9NiGZuhwFb/padRRuphJtJaZZtHg2P7OR8AJjC0qlGAx2sUnEsRP/KHPdqkgmy7FtSqOXtb2uQvbg==
   dependencies:
     "@date-io/luxon" "^3.0.0"
     "@dnd-kit/core" "^6.0.7"